Analysis of a gene required for membrane fusion during nematode spermiogenesis
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AbstractC. elegans spermatids contain large vesicles called membranous organelles (MOs) that fuse with the plasma membrane during maturation to spermatozoa. This fusion is essential since mutations in the gene fer-1 block MO-plasma membrane fusion and result in abnormal spermatozoa. To determine the function of the fer-1 gene product during sperm maturation, I have cloned and sequenced the gene and several cDNAs. fer-1 is approximately 8.6kb in length and encodes a 6.3kb sperm-specific transcript. In situ hybridization experiments have shown fer-1 expression is limited to the primary spermatocytes, the cells in which the MOs are formed. fer-1 is predicted to encode a 235kD basic integral membrane protein (FER-1) that is highly charged and rich in lysine and glutamic acid. Database searches revealed FER-1 is similar to several predicted human proteins of unknown function. Mutations have been identified for four of the eleven fer-1 alleles, all of which cause amino acid changes in this predicted protein. FER-1 contains no recognizable functional motifs other than a single transmembrane domain at the C-terminus, a feature common to viral membrane fusion proteins. Antibodies raised against FER-1 and used for immunolocalization and western blot experiments did not yield reliable results. The work presented in this dissertation gives some evidence for my hypothesis that FER-1 is a membrane fusion protein, although the membrane fusion defect observed could be an indirect result of fer-1 mutations.
Degree ProgramGraduate College
Molecular and Cellular Biology