Análise proteômica das glândulas de veneno e acessória durante o ciclo de produção de veneno e a influência da inervação noradrenérgica na síntese de proteínas foi verificada. Nossos dados mostram que a síntese de proteínas envolvidas no processo de síntese e secreção de proteínas está aumentada nos estágios ativados da glândula de veneno e que a estimulação da inervação noradrenérgica regula a síntese de algumas proteínas importantes para estes processos. Mostramos pela primeira vez, a presença de várias toxinas no estágio quiescente da glândula e que a produção e secreção de toxinas ocorrem de maneira não sincronizada. Na glândula acessória verificamos uma modulação na síntese de algumas proteínas da glândula após a extração de veneno. Mostramos também a presença de várias toxinas e de inibidores de enzimas do veneno nesta glândula. A composição proteômica das glândulas do aparelho glandular de veneno de serpente contribuirá para um melhor conhecimento dos mecanismos de produção e secreção de veneno e para os estudos das toxinas e suas diversidades. / Proteomic analysis of venom gland and accessory gland during venom production cycle and the influence of noradrenergic innervation on protein synthesis of venom gland were verified. Our data show that the synthesis of proteins involved in the process of synthesis and secretion of proteins is increased in activated stages of venom gland and the sympathetic outflow regulates the synthesis of some proteins that is important to this process. For the first time we showed that many toxins are present in quiescent stage of venom gland and the production and secretion of toxins is not synchronized. Regarding the accessory gland, we verify that the syntheses of some protein of gland were regulated after venom extraction. We also showed the presence of some toxins of the venom and enzyme inhibitors in this gland. The proteomic composition of snake venom gland apparatus will contribute to better understand the mechanisms involved in venom gland activation and consequently, venom production. These data will also contribute to the studies on snake toxins and their diversities.

<p>Nuts of all kinds are common ingredients in food. For nut allergy sufferers the frequent use of nuts cause problems and "hidden" nuts in food products may elicit allergic reaction when such foods are consumed. Methods for detecting and quantifying walnut (and other nuts) with high sensitivity and specificity are therefore very important.</p><p>The objective of this project was to verify the specificity of a rabbit antiserum against walnut with immunodiffusion and to determine the size of the dominant walnut antigens with Western blotting. In addition, a commercial sandwich ELISA for walnut quantification was validated and compared with a qualitative real-time PCR.</p><p>The rabbit antiserum proved to be less specific but after absorption with cross-reacting nuts and seeds it showed high specificity. The ELISA kit reacted, except for walnut, with pecan and slightly with other nuts and seeds tested. The PCR showed an absolute specificity to walnut. As low levels as 2.5mg walnut/kg can be quantified with the ELISA. This is 8 to 100 fold less than with the PCR method. It is therefore concluded that the ELISA kit is more sensitive than the PCR method but the PCR method is more specific than the ELISA kit.</p>

Nuts of all kinds are common ingredients in food. For nut allergy sufferers the frequent use of nuts cause problems and "hidden" nuts in food products may elicit allergic reaction when such foods are consumed. Methods for detecting and quantifying walnut (and other nuts) with high sensitivity and specificity are therefore very important. The objective of this project was to verify the specificity of a rabbit antiserum against walnut with immunodiffusion and to determine the size of the dominant walnut antigens with Western blotting. In addition, a commercial sandwich ELISA for walnut quantification was validated and compared with a qualitative real-time PCR. The rabbit antiserum proved to be less specific but after absorption with cross-reacting nuts and seeds it showed high specificity. The ELISA kit reacted, except for walnut, with pecan and slightly with other nuts and seeds tested. The PCR showed an absolute specificity to walnut. As low levels as 2.5mg walnut/kg can be quantified with the ELISA. This is 8 to 100 fold less than with the PCR method. It is therefore concluded that the ELISA kit is more sensitive than the PCR method but the PCR method is more specific than the ELISA kit.

In this research, a method for site-selective attachment of synthetic molecules into glycoproteins using Boronic acid (BA)-directed tosyl chemistry is proposed. The synthetic BA-tosyl chemical probes are composed of boronic asid as a affinity ligand, a tosyl group as a reactive group and a terminal alkyne group for reporting. In neutral and alkaline environment, boronic acid can act as a targeting head to react with the cis-diol of carbohydrates and therefore forms a covalently reversible boronic diester ring. The newly formed boronate ring can withdraw the probe moeular close to the molecular surface of glycoproteins of interest. Followed by a SN2 reaction with the nucleophilic residues of labeled glycoproteins, the report alkyne group can covalently shift to the protein surface apart from the BA-tosyl skeleton. With the competition of polyols, the BA modified carbohydrates can be recovered to the native glycan structures. The traceless labeling strategy developed in the work has been demonstrated in the specific interaction with a known glycoprotein feutin with negatives controls. We believe that the successful development of this methodology can certainly accelerate the study of glycoproteomics and glycobiology.

Arginine vasopressin (AVP) is a hypothalamic nonapeptide which regulates the hypothalamic-pituitary-adrenal axis response to stress by stimulating the secretion of adrenocorticotropin (ACTH) from corticotroph cells of the anterior pituitary. This effect is mediated by binding of AVP to the pituitary vasopressin receptor (V1bR). The V1bR belongs to the G protein-coupled receptor (GPCR) super family. Repeated stimulation of anterior pituitary cells with AVP has been shown to produce a loss of responsiveness to subsequent AVP stimulation. This phenomenon appears to be mediated by desensitisation of the V1bR, and may be due to phosphorylation of the receptor by G protein-coupled receptor kinase 5 (GRK5). The aim of this research was to establish and validate methods that would allow the role of GRK5 in the desensitisation of V1bR to AVP stimulation to be investigated. As no isoform specific inhibitors for GRK5 were available, HEK293 cells transiently transfected with the rat V1bR were used as a model system for this research. This allowed RNA interference (RNAi) to be used to knockdown GRK5 expression. The protocol for RNAi-mediated knockdown of GRK5 was established as part of this research. Protocols for Western blotting and qRT-PCR were also established to allow the RNAi-mediated knockdown of GRK5 protein and mRNA to be measured. Transfection of HEK293 cells with 10nM GRK5-targeting small interfering RNAs (siRNAs) reduced the expression of GRK5 protein to 53.4% ± 3.4% (mean ± SEM) of that seen in untreated control cells at 84 hours after transfection, while GRK5 mRNA levels were reduced to 28.7% ± 1.9% (mean ± SEM) of that of control cells 48 hours after transfection. An experimental protocol was designed in this research that would coordinate the RNAi-mediated knockdown of GRK5 with transient transfection of the HEK293 cells with the rV1bR. Since, activated V1bRs couple to Gq/11 and stimulate the production of inositol phosphates (IPs), the responsiveness of the V1bR can be determined by measuring the accumulation of [H³]-IPs in cells labelled with [H³]-myo-inositol. In the protocol designed, the effect of GRK5 knockdown on V1bR desensitisation is determined by stimulating HEK293 cells expressing the rV1bR (and previously transfected with GRK5-targeting siRNA) with 0nM or 100nM AVP for 0, 5, 15, 30 or 60 minutes, and comparing the accumulation if IPs over time with that of cells that are not transfected with GRK5-targeting siRNA. This protocol can be used in future to investigate the role of GRK5 in V1bR desensitisation, and may be adapted to determine if other GRK isoforms are involved in V1bR desensitisation.

Arylamine N-acetyltransferases (NATs) were partially purified from human breast tumor tissues with complete separation of the isoforms in DEAE-Cellulose ion-exchange step. NAT with activity towards p-aminobenzoic acid (PABA) was isolated and purified from human breast tumor with 77 % yield and a purification factor of 5-fold. NAT with activity towards sulfamethazine (SMZ) was isolated and purified from human breast tumor with 21 % yield and a purification factor of 3-fold. Further purification attempts by Blue Sepharose affinity column chromatography resulted in the complete loss of both enzyme activities. The NAT1 purified from human breast tumor tissues had a molecular weight (Mr) value of about 27600 and an isoelectric point (pI) around 4.8, as confirmed by SDS-PAGE, IEF and Western blotting analysis. With immunohistochemical analysis, level of intensity of NAT1 immunostaining was observed to be going from weak in reduction mammoplasty samples to strongest in malignant breast tissue. The interindividual variation in the conjugation of p-aminobenzoic acid (PABA) and of sulfamethazine (SMZ) by cytosolic arylamine N-acetyltransferases (NATs) were investigated in 30 human breast tumor and matched samples. The average specific activity against PABA was calculated as 13&amp / #61617 / 2 pmole/min/mg protein for breast control NATs, and 20&amp / #61617 / 3 pmole/min/mg protein for breast tumor NATs. The average specific activity against SMZ was calculated as 12&amp / #61617 / 2 pmole/min/mg protein for breast control NATs, and 34&amp / #61617 / 6 pmole/min/mg protein for breast tumor NATs. Wilcoxon test revealed that the difference between the control and tumor groups is statistically significant with respect to the NAT1 activities as well as NAT2 activities. In three (3/30, 10%) patients tumor and tumor-free breast tissue NAT1 activity was not detectable. Among control tissues, the percentage of measurable NAT2 activity was 77% (23/30), while in tumor tissues it increased to 91%. Chemotherapy treatment was observed to have a slight inhibitory effect on mean NAT1 and NAT2 activities. There was an indication of a possible negative association with mean NAT1 activity and estrogen receptor status, while mean tumor NAT2 activity was observed to increase among estrogen receptor positive patients. Grade of malignancy seems to be positively associated with NAT1, but no such association could be suggested for NAT2 enzyme. Menopausal state of the patient was suggested to have a significant effect on NAT2 activity. Genotype determination of NATs revealed that NAT1*4 and NAT2*5A allele being most common among 10 breast cancer patients. NAT1*11 allele was prevalent among postmenopausal women. The putative rapid NAT1 genotypes was found to display lower control and tumor mean NAT1 activities compared to normal NAT1 genotypes. Among slow NAT2 acetylators, mean tumor NAT2 activities was found to be significantly higher than respective controls.

High quality reagents are preconditions for high performance protein analyses. But despite progress in some techniques, e.g. mass spectrometry, there is still a lack of affinity-based detection techniques with enhanced precision, specificity, and sensitivity. Building on the concept of multiple affinity recognition reactions and signal amplification, a proximity ligation assay (PLA) was developed as a molecular tool for analyzing proteins and their post-translational modification and interactions. PLA enhanced the analysis of protein expression levels and post-translational modifications in western blotting (Paper I), which had elevated sensitivity and specificity, and an ability to investigate protein phosphorylation. A general and straightforward method was established for the functionalization of affinity reagents through adding DNA strands to protein domains for protein analysis in medicine (Paper II). A method for protein domain-mediated conjugation was developed to simplify the use of recombinant affinity reagents, such as designed ankyrin repeat protein (DARPin), in DNA-mediated protein analyses. Alzheimer’s disease (AD) is characterized by progressive cognitive decline and memory impairment, and amyloid-beta plaques and neurofibrillary tangles (NFT) in the brain are clinical hallmarks of the disease. In order to understand the mechanisms underlying the formation of NFT, in situ PLA was used to explore the role of microtubule affinity related kinase 2 (MARK2) in phosphorylating tau protein during the pathological progress of AD (Paper III). The analyses of roles of MARK proteins 1-4 in phosphorylating tau protein in cells and in post-mortem human brains were performed in Paper IV. The focus of this thesis was the study of post-translational modifications and interactions of proteins in medicine. Procedures for high performance protein analysis in western blotting via proximity ligation were developed, and a functionalization method for recombinant affinity reagents in DNA-mediated protein analysis was established. These and other techniques were used to investigate the roles of tau-phosphorylating MARK family proteins in AD.

Submitted by Hiolanda Rêgo (hiolandarego@gmail.com) on 2016-07-15T18:12:01Z No. of bitstreams: 1 Dissertação_ICS_ Marcos Borges Ribeiro.pdf: 1012544 bytes, checksum: cd3041816b8e33f18036ad6952db5f5d (MD5) / Approved for entry into archive by Delba Rosa (delba@ufba.br) on 2016-12-19T14:20:58Z (GMT) No. of bitstreams: 1 Dissertação_ICS_ Marcos Borges Ribeiro.pdf: 1012544 bytes, checksum: cd3041816b8e33f18036ad6952db5f5d (MD5) / Made available in DSpace on 2016-12-19T14:20:58Z (GMT). No. of bitstreams: 1 Dissertação_ICS_ Marcos Borges Ribeiro.pdf: 1012544 bytes, checksum: cd3041816b8e33f18036ad6952db5f5d (MD5) / A brucelose canina é uma infecção bacteriana contagiosa, zoonótica, causada pela Brucella canis, responsável por aborto e infertilidade. A brucelose é uma doença de importância mundial pelo prejuízo ocasionado tanto para a saúde publica como para a economia nacional. O diagnóstico baseia-se principalmente na sorologia devido a inespecificidade dos sinais clínicos. Vários métodos têm sido descritos e utilizados para diagnóstico, porém a maioria comercialmente disponível produz resultados falsos positivos. Neste trabalho foi comparado o perfil de reconhecimento de Ig G sérica a dois extratos solúveis de Brucella canis, preparados de diferentes formas. Os soros foram analisados por ELISA Indireto com os dois extratos solúveis obtidos por calor e Ultra-som. Foram testadas 765 amostras de soros de cães domiciliados da cidade de Salvador e área metropolitana com sorologia desconhecida, 92 amostras de soros testadas no Centro de Controle de Zoonoses da cidade de São Paulo (CCZ-SP) pelo método IDGA com antígeno de Brucella ovis sendo 45 positivas e 47 amostras negativas. Para o cálculo do valor de corte foram utilizadas 21 amostras de soros de filhotes de cães saudáveis provenientes do biotério do Centro de Pesquisa Gonçalves Muniz (CPqGM-Fiocruz) – Salvador –Ba. O perfil eletroforetico foi analisado por SDS-PAGE em sistema desnaturante e a reatividade dos antígenos solúveis foi avaliada pelo ELISA e Western Blotting, comparando diferentes grupos de soros. A comparação entre os ELISAs com ambos antígenos foi feito com todos os 857 soros. O ELISA com extrato solúvel obtido por calor indicou uma positividade de 10% (n=79) com valor de D.O de limite de corte de 0,235, já o ELISA com extrato solúvel obtido por ultra-som indicou uma positividade de 24% (n=187) com valor de D.O de limite de corte de 0,350. A análise estatística de correlação dos resultados encontrados nos estudos dos dois antígenos obtido por calor e ultrasom foi de 0,68. Os 92 soros do CCZ-SP testados pela IDGA foram utilizados para avaliar a especificidade, sensibilidade, valores preditivos positivo e negativo e eficiência dos ELISAs, sendo 51%,94%, 89%, 67% e 73% para o ELISA com extrato obtido por calor e de 69%, 83%, 80%,74% e 76% para o ELISA com o extrato obtido por ultra-som, respectivamente. A concordância entre os ELISAs utilizando os dois extratos solúveis dada pelo índice Kappa foi de κ= 0,38. O Elisa realizado com extrato solúvel obtido por calor mostrou concordância com a IDGA de κ=0,45 e o ELISA utilizando extrato solúvel obtido por ultra-som e a IDGA com κ= 0,52. A imunoreatividade do extrato antigênico solúvel de B. canis obtido por calor (extrato aquecido), utilizando soros de animais positivos na IDGA e ELISA, apresentou com maior freqüência as bandas 65 KDa, 58 KDa, 56 KDa, 18 KDa e 12 KDa e o extrato obtido por ultra-som as bandas 68 KDa, 52 KDa, 46 KDa, 38 KDa, 28 KDa, 18 KDa. Os antígenos utilizados para os ELISAs aquecido e sonicado, mostram diferentes perfis eletroforético em análise pela técnica SDSPAGE, sugerindo diferentes composições protéicas. Os extratos analisados por ELISA, apesar de apresentarem bons valores de controle de qualidade, sendo o de ultra-som melhor que os aquecidos, necessitam ser avaliados quanto a sua reatividade com soros de animais com diagnóstico de brucelose canina confirmados por isolamento bacteriano ou por PCR.

Made available in DSpace on 2016-08-12T18:48:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-12-07. Added 1 bitstream(s) on 2016-08-12T18:51:10Z : No. of bitstreams: 1 000865801_20171231.pdf: 1061346 bytes, checksum: efe45af74713a03a299062d24c3f7820 (MD5) Bitstreams deleted on 2018-01-02T17:04:40Z: 000865801_20171231.pdf,. Added 1 bitstream(s) on 2018-01-02T17:05:44Z : No. of bitstreams: 1 000865801.pdf: 3646553 bytes, checksum: e4296295ee6540afe7731bb02d9b4994 (MD5) / A tripanossomíase Americana, mais conhecida por doença de Chagas, é transmitida por triatomíneos infectados pelo agente etiológico Trypanosoma cruzi. Desde que foi descrita pela primeira vez em 1909, a doença tem se expandido pelo mundo infectando milhões de pessoas, principalmente na America Latina, onde ela é endêmica. Atualmente, apenas dois fármacos estão disponiveis para o tratamento, o nifurtimox, que não é usado no Brasil, e o benzonidazol, que teve sua produção industrial bastante reduzida. No entanto, ambos os fármacos tem ações limitadas. Assim, a busca de novas substâncias e a compreensão do mecanismo de resistência aos fármacos tripanossomicidas disponíveis e aos que ainda estão em fase de pesquisa, tem sido motivo de vários estudos. Alguns estudos relatam um aumento na produção de enzimas que atuam na defesa celular, as quais, provavelmente, poderiam ser responsáveis pela resistência do parasito. Algumas enzimas têm funções importantes na sobrevivência e crescimento dos parasitos: superóxido dismutase (SOD), metaloenzima que elimina radicais superóxido ao convertê-los em peróxido de hidrogênio e oxigênio molecular; old yellow enzyme (OYE), uma NADPH flavina oxidoredutase que pode estar envolvida na redução de substâncias tripanossomicidas, e peroxiredoxina (Prx), que catalisa a redução de peróxidos. Por meio de Western blotting analisou-se as modificações em nível de expressão das enzimas SOD, OYE e Prx em cepas de T. cruzi tratadas ou não com um composto derivado benzofuroxânico, LAPDESF-BZFS (6-((metil)benzo[c](2-carbamoilidrazona)-1-Nóxido-1,2,5-oxadiazol). O IC50 (índice de citotoxicidade) desse composto foi de 6,88 µg/mL, e promoveu alterações na expressão das enzimas Prx e OYE, provavelmente promovendo o estresse oxidativo em formas epimastigotas. / The American trypanosomiasis, also known for Chagas disease, and transmitted for infected triatomine by etiological agent Trypanosoma cruzi. Since it was first described in 1909, this disease has expanded the world infecting millions of people, mostly in Latin America, where it is endemic. Currently only two drugs are available for Chagas disease treatment, nifurtimox, which is not used in Brazil, and benznidazole, which had its much reduced industrial production. However, both drugs have limited actions. Thus, the search for new compounds and to understand the mechanism of resistance to trypanocidal drugs available and that are still in the research phase, have been the subject of several studies. Some studies report an increase in the production of enzymes that action in cellular defense, which probably could be responsible for parasite resistance. Some enzymes have important functions in the survival and growth of parasites: superoxide dismutase (SOD), metalloenzyme that eliminates superoxide radicals to convert them hydrogen peroxide and molecular oxygen; old yellow enzyme (OYE) a NADPH- flavin oxidoreductase that may be involved in the reduction of trypanocidal substances and peroxiredoxin (Prx), which catalyzes the reduction of peroxides. By means of Western blotting analyzed for changes in expression level of SOD, Prx and OYE in strains of T. cruzi treated or not with a compound derived benzofuroxânico, LAPDESFBZFS ( 6 - (( methyl) benzo [c ] (2- carbamoilidrazona ) -1 -N-oxide -1,2,5- oxadiazol ). The CI50 (cytotoxicity index) of this compound was 6.88 µg/mL, and promoted changes in the expression of PRX and OYE enzymes, probably by promoting oxidative stress in epimastigotes .

Submitted by INAÊ CRISTINA REGATIERI null (iregatieri@hotmail.com) on 2016-10-25T11:32:21Z No. of bitstreams: 1 Tese_Inae_Cristina_Regatieri.pdf: 1026482 bytes, checksum: 93ce299c664eb44473c4cdf6c6496fb4 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-10-31T17:37:43Z (GMT) No. of bitstreams: 1 regatieri_ic_dr_jabo.pdf: 1026482 bytes, checksum: 93ce299c664eb44473c4cdf6c6496fb4 (MD5) / Made available in DSpace on 2016-10-31T17:37:43Z (GMT). No. of bitstreams: 1 regatieri_ic_dr_jabo.pdf: 1026482 bytes, checksum: 93ce299c664eb44473c4cdf6c6496fb4 (MD5) Previous issue date: 2016-10-19 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O transportador de monocarboxilato isoforma 1 (MCT1), presente na membrana das hemácias, e sua proteína auxiliar CD147 têm como função transportar H+ e lactato do plasma para dentro das hemácias, mantendo assim, a homeostase ácido-base e retardando a acidose sistêmica e fadiga muscular. Dessa forma, o objetivo desse estudo foi comparar as quantidades das proteínas MCT1 e CD147 em hemácias de cavalos Árabes e Quartos de Milha com diferentes níveis de desempenho atlético. Além disso, objetivou-se buscar por polimorfismos para os genes MCT1, CD147, DMRT3 e PDK4, a fim de checar associações entre os polimorfismos e o desempenho nas raças. Cavalos Árabes e Quartos de Milha foram divididos em dois grupos de acordo com o desempenho em provas de enduro e provas de corridas, respectivamente. A quantidade de MCT1 e CD147 na membrana plasmática das hemácias foi determinada por western blotting com unidades arbitrárias de densidade óptica (OD) e anticorpos reagentes à espécie humana anti-MCT1 e anti-CD147. Os dados para as quantidades de proteínas foram analisados pelo PROC MIXED do SAS. O modelo incluiu a idade como covariável e os efeitos fixos de sexo, raça e grupo de desempenho dentro de raça. As correlações foram analisadas pelo teste de Pearson pelo procedimento PROC CORR. P-valores <0,01 foram considerados estatisticamente significantes. Os polimorfismos dos genes foram analisados por sequenciamento (MCT1 e CD147), PCR-RFLP (DMRT3) e ARMS-PCR (PDK4). Os pacotes estatísticos Genetics, Lattice e GenABEL foram utilizados para comparar as frequências dos grupos de desempenho no software R, com o teste exato de Fisher a 5% de significância. As proteínas MCT1 e CD147 foram encontradas nas hemácias de todos os animais. A quantidade de MCT1 foi significativamente (p<0,0001) maior em Quartos de Milha (2,99 ± 0,35 OD) do que em Árabes (1,04 ± 0,08 OD). Quartos de Milha (3,23 ± 0,38 OD) também apresentaram maior conteúdo de CD147 do que Árabes (0,88 ± 0,06 OD). Não houve diferença estatística nas quantidades de proteínas para os grupos de desempenho de ambas as raças. Correlação positiva foi encontrada entre as quantidades de MCT1 e CD147 (r=0,95; p<0,0001). O Alelo A dos polimorfismos Lys457Gln:1573A>C do gene MCT1 e Ile51Val:168A>G do gene CD147 estavam fixados em ambas as raças. Um novo polimorfismo (AY457175.1:c1498G>A) foi encontrado na sequência do gene MCT1. Para o DMRT3, todos os animais apresentaram o alelo C fixado para o polimorfismo. Árabes mostraram maior frequência para o alelo G do que Quartos de Milha (p<0,01) para o polimorfismo no gene PDK4. Entretanto, não houve diferença entre os grupos de desempenho para as duas raças. Dessa forma, conclui-se que Quartos de Milha têm maiores quantidades de MCT1 e CD147 do que Árabes. Não foi possível determinar a influência dos polimorfismos nos genes MCT1, CD147 e DMRT3 no desempenho atlético das duas raças visto que seus alelos estavam fixados. Além disso, houve diferença significativa nas frequências do polimorfismo no gene PDK4 entre Árabes e Quartos de Milha, mas não houve diferença entre os grupos de desempenho. / Monocarboxylate transporter isoform 1 (MCT1), present in the red blood cell membranes and its ancillary protein CD147 have as function transport H+ and lactate ions from the plasma into the red blood cells, thereby maintaining acid/base homeostasis and retarding systemic acidosis and muscular fatigue. Thereby, the aim of this study was to compare the amount of MCT1 and CD147 proteins in the red blood cells of Arabian and Quarter Horses with different levels of athletic ability. Furthermore, we investigated polymorphisms for MCT1, CD147, DMRT3, and PDK4 genes in Arabian and Quarter Horses in order to check associations between the polymorphisms and the performance in these breeds. Arabian horses were divided into two groups according to their performance in endurance competition and Quarter Horses were separated by its performance in races, determined by Speed Index. The amount of MCT1 and CD147 proteins in the plasma membrane of red blood cells was determined by western blotting analysis with arbitrary optical density units (OD), using a human specific anti-MCT1 and anti- CD147 antibody. Data for the amounts of proteins were analyzed using the PROC MIXED procedure of SAS software. The model for the analysis included the effects of sex, breed and performance group within breed as fixed effect and age as covariate. The correlations were analyzed by Pearson correlation test using the PROC CORR procedure of SAS software. P values <0.01 were considered statistically significant. Polymorphisms of the genes were analyzed by sequencing (MCT1 and CD147), PCR-RFLP (DMRT3) and ARMS-PCR (PDK4) techniques. The statistical packages Genetics, Lattice and GenABEL were used to compare the frequencies of the groups using the software R, with the Fisher's exact test being performed with significance level of 5%. MCT1 and CD147 proteins were found in the red blood cell membranes of all studied animals. The amount of MCT1 was significantly (p<0.0001) higher in Quarter Horses (2.99 ± 0.35 OD) than in Arabians (1.04 ± 0.08 OD). Quarter Horses (3.23 ± 0.38 OD) also showed bigger contents of CD147 than Arabians (0.88 ± 0.06 OD). There was not statistical difference in the amounts of MCT1 and CD147 between the performance groups of both breeds. Positive correlation was found between the amounts of MCT1 and CD147 (r=0.95; p<0.0001). The A allele from the polymorphisms Lys457Gln:1573A>C of MCT1 and Ile51Val:168A>G of CD147 gene, were fixed in both breeds. A new polymorphism (AY457175.1:c1498G>A) was found in the MCT1 gene sequence. For DMRT3 mutation, all the animals shown to have the C allele fixed for the polymorphism. Arabians showed significant greater frequency of the G allele than Quarter Horses (p<0.01) for the PDK4 polymorphism. However, there was not difference between the groups of performance for both breeds. In summary, it follows that the Quarter Horses have greater amount of MCT1 and CD147 proteins than Arabian. It was not possible to determine the influence of polymorphisms in MCT1, CD147 and DMRT3 genes in the athletic performance of these breeds since they had alleles fixed. There was a significant difference in the frequencies of the PDK4 polymorphism between Arabians and Quarter Horses, but there was not difference between the performance groups. / FAPESP: 2012/24193-0 / FAPESP: 2012/20697-9