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This dissertation consists of four chapters. The first chapter provides an in-depth background of synthetic receptors for recognitions of phosphorylated molecules. This chapter covers synthetic receptors developed within the last two decades, and it focuses on the diverse functionalities and detection techniques involved in the receptor design. Chapter 2 discusses the synthesis and employment of a metalated receptor for the selective recognition of organic phosphates and phospho-amino acids, and describes a receptor with a pseudo tetrahedral cavity, which was found to be selective to phosphate, was synthesized utilizing a new and efficient synthetic route. UV-Vis titrations were used to determine binding constants for various organic phosphates and phospho-amino acids. The receptor:Cu(II) complex was found to differentiate the degree and size of phosphate substitutions. Chapter 3 describes the synthesis and application of a type of differential receptors for the recognition of phosphorylated tri-peptides from regular tri-peptides. The tri-peptide couples described in this chapter were part of sequences in protein Filamentous R-synuclein, which was discovered to have a close relation to Parkinson's disease. Extensive Ser129 phosphorylation was observed in diseased brains. Both solid phase and solution phase differential receptors were obtained in the investigations of peptide differentiation. A series of screening methods were applied to narrow down the system combinations. Linear discrimant analysis (LDA) statistical analysis generated a large spatial separation among six tripeptides. Chapter 4 describes the synthesis of a boronic acid based receptor for carboxy and phospho sugars recognition. Due to the large affinity to gluconic acid, which is the only product of enzyme catalyzed glucose oxidation, this receptor was successfully applied in determination of glucose concentration in human serum.

G protein-coupled receptors (GPCRs) are 7 transmembrane domain proteins capable of initiating cellular responses following ligand binding. GPR92 is expressed in the central nervous system (CNS) and is demonstrated to be involved in pain signalling via neurons of the spinal cord and dorsal root ganglion (DRG). Activated by the endogenous lipid lysophosphatidic acid (LPA), GPR92 is now considered the 5th LPA receptor. There remains controversy regarding GPR92 pharmacology however, as studies show another endogenous lipid, farnesyl pyrophosphate (FPP), also activates GPR92 with similar potency and efficacy to LPA. LPA-induced activation of GPR92 results in increased intracellular calcium (Ca2+) and cAMP. Furthermore, GPR92 mediates neurite retraction via Rho kinase and activates the cAMP responsive element-binding (CREB) protein. This transcription factor is important in synaptic plasticity and regulates the expression of many neuronal genes including brain derived neurotrophic factor (BDNF), yet the role of GPR92 in the brain has not been explored. Here, I describe the pharmacology and signalling of GPR92, with preliminary data describing its expression. I utilise a cell line lacking endogenous LPA responsiveness (B103 rat neuroblastoma) in which I stably express GPR92. Using intracellular Ca2+ changes and CREB phosphorylation as read-outs, I find FPP to be the most potent and efficacious ligand. The similarly structured lipid geranylgeranyl pyrophosphate (GGPP) produced comparable results to FPP. GPR92-mediated CREB phosphorylation has been described in a mouse model of pain. The ligands which induce this response however, have not been assessed. I describe for the first time, ligand-induced CREB phosphorylation via GPR92, and found that FPP causes the most robust CREB response. LPA and GGPP also induced GPR92-mediated CREB phsphorylation. Furthermore, I find that GPR92 mediates a novel Gq-dependent, Ca2+ independent, signalling pathway resulting in CREB phosphorylation. In addition, I examine GPR92 expression in the CNS using reverse-transcriptase polymerase chain reaction (RT-PCR) and in situ hybridisation. GPR92 is expressed throughout the brain, with particularly high expression in 7 the brain stem, DRG, and hippocampus. In situ hybridisation revealed a distinct expression pattern confirming high levels of GPR92 mRNA in the hippocampal region. GPR92 mRNA is also observed in the cortex, habenula, thalamus and hypothalamus. I also report the expression of the FPP synthesising enzyme FPP synthase (FPPS). Relative expression levels of FPPS between CNS regions are similar to GPR92. Preliminary data suggests FPP is capable of mobilising Ca2+ in hippocampal neuronal and non-neuronal cells. These data suggest an important role for GPR92 in the brain where it, and the enzyme involved in generating one of its endogenous ligands, are highly expressed.

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Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002. / On t.p. "1̳" is subscript. Includes bibliographical references (leaves 114-141). Also available in electronic version. Access restricted to campus users.

Thesis (Ph.D.) - University of Queensland, 2005. / Includes bibliography.

Thesis (Ph.D.)--Aberdeen University, 2008. / Title from web page (viewed on Mar. 2, 2009). Includes bibliographical references.