Several vital cellular processes are preformed by large ribonucleoprotein (RNP) complexes. In archaeal and eukaryotic cells one example of these essential RNP particles is the box C/D sRNP. In archaea, this complex is responsible for methylation of ribosomal RNA (rRNA) and transfer RNA (tRNA) during their maturation. Archaeal fibrillarin (aFib) is the 2'-O methyltransferase responsible for catalysis by this complex. In this work we have identified the ability of aFib from Sulfolobus acidocaldarius to form dimers at biologically relevant concentrations and the structural determinants essential for this association. Based on our model we have predicted the ability of aFibs to form dimers in different archaeal and eukaryotic species. The ability of aFibs and their eukaryotic homologs to potentially adopt multiple conformations provides insight into the dynamics of the box C/D sRNP complex. As observed in the study of other essential RNP particles, the ability of these complexes to be conformationally diverse is integral to efficient catalysis of their varied substrates. / viii, 74 leaves ; 29 cm.

Intermediate filaments are fibrous proteins, appearing in a wide variety of tissue specific forms. The function of these proteins is poorly understood, although they are commonly believed to perform a structural role in the cell. Evidence suggests that the role these proteins play may be more dynamic than was previously believed. To gain more insight into their normal in vivo function, a single-chain monoclonal antibody has been constructed to serve as a specific reagent which can disrupt the intermediate filament network in vivo. The work presented in this thesis represents the first step in an approach which involves the use of single-chain monoclonal antibodies as specific reagents to target and disrupt the function of intracellular proteins. / The polymerase chain reaction was used for the cloning and modification of the heavy and light chain variable regions of the murine monoclonal antibody produced by the TIB 131 hybridoma. The variable regions of the light and heavy IgG chains were initially amplified from cDNA using degenerate 5$ sp prime$ primers and 3$ sp prime$ primers complementary to the constant region of the appropriate chain. The amplification products were cloned individually, sequenced, then modified to include restriction sites suitable for cloning into an expression vector. The two modified variable regions were cloned into an expression vector, and when expressed in either bacteria or in a rabbit reticulocyte lysate system, yielded a protein of the expected molecular weight.

A preliminary analysis of translation initiation has been carried out using the model system Drosophila melanogaster. These efforts have focussed on identifying the homolog of mammalian of mammalian eIF-4F, a complex of three subunits; eIF-4E which binds the mRNA cap, eIF-4A which has ATP-dependent RNA helicase activity, and eIF-4$ gamma$, of unknown function. Attempts to clone the genes encoding subunits of eIF-4F have led to the isolation of two novel genes. A molecular screen for members of the DEAD family of RNA helicases that includes eIF-4A led to the isolation of a gene which encodes the putative homolog of a yeast protein involved in ribosome assembly. From a complementation screen for suppressors of mutants of the Saccharomyces cerevisiae cap binding subunit, was isolated a Drosophila cDNA encoding a putative ribosomal protein, RpS15a, of the 40S subunit. Further characterization of the mechanism of suppression has shown that overexpression of RpS15a stabilizes the yeast eIF-4E protein suggesting a direct interaction between eIF-4E and the ribosome. Our work has shown that unlike the mammalian system, two cap binding proteins exist in Drosophila. The molecular analysis of cDNA clones encoding Drosophila eIF-4E suggests that the proteins result from alternatively spliced mRNAs expressed from a single gene. The biochemical characterization of Drosophila eIF-4A has shown that eIF-4A is part of a complex similar in size to mammalian eIF-4F but that unlike mammals, one eIF-4A protein is produced from a single gene and is regulated by phosphorylation. Phosphorylated eIF-4A is present in oocytes and early embryos but not in later embryos. Phosphorylated eIF-4A accumulates on the 48S initiation complex suggesting that a mechanism involving the post-translational regulation of eIF-4A affects the translation of maternal mRNAs in the oocyte and early embryo.

Thesis (Ph.D.)--McMaster University (Canada), 1996. / Source: Dissertation Abstracts International, Volume: 57-10, Section: B, page: 6096. Adviser: J. P. Capone.

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2008. / Includes bibliographical references (leaves 215-246). Also available in electronic version.

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references (leaves 215-227). Also available in electronic version. Access restricted to campus users.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 90-97). Also available on the Internet.

Thesis (PH. D.)--Michigan State University. Genetics, 2008. / Title from PDF t.p. (viewed on Sept. 2, 2009) Includes bibliographical references. Also issued in print.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 90-97). Also available on the Internet.

Thesis (Ph. D.)--Brigham Young University. Dept. of Chemistry and Biochemistry, 2006. / Includes bibliographical references.