Genetics - Theses
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ItemMammalian homologues of the stoned gene(University of Melbourne, 2004)Genetic and biochemical studies have shown that the stoned gene of Drosophila melanogaster is essential for normal recycling of synaptic vesicles. The dicistronic stoned transcript encodes two products; STNA, a novel protein, and STNB which has similarity with the ? subunits of adaptor complexes. However it is not yet known specifically how these proteins function during synaptic transmission. This investigation sought to identify murine homologues of the stoned proteins, in order to further our understanding of these essential neural components. During this study, two STNB homologues were identified, mSTNB1 and mSTNB2, which also have similarity to the ? adaptins. Although no sequence homologues of STNA appear to be present in mammalian genomes, this does not exclude the possible existance of a functional STNA homologue. The characterisation of mSTNB1 revealed that the mRNA transcript is widely expressed. However unlike STNB, neither the mSTNB1 mRNA or protein is enriched in the brain. The mSTNB1 protein has also been found in a range of cell lines, including CHO cells. An analysis of heart cross-sections revealed that mSTNB1 is abundant in a subset of non-neuronal cells. Comparison of mSTNB1 to subcellular markers in CHO cells indicated that mSTNB1 is associated with punctate structures, where it partially co-localises with the Golgi-associated 58kDa protein. This may represent the ER-to-Golgi intermediate compartment (ERGIC), which is involved in the early secretory pathway. Consistent with this, mSTNB1 is not found associated with the endocytic trafficking compartments. These observations have led to the hypothesis that the STNB family of proteins may be involved in the trafficking of large vesicular carriers, such as synaptic vesicle precursors or the ERGIC, rather than the biogenesis of small vesicles.