| Summary: | 碩士 === 臺北醫學大學 === 醫學研究所 === 95 === Guanylyl cyclase (GC) is known to transmit signaling by synthesizing of intracellular cyclic GMP. We have previously described an orphan GC receptor on mouse sperm (mouse GC-G) which is able to regulate sperm motility and capacitation-associated protein tyrosine phosphorylation. Here, we reported the identification and functional characterization of its apparent homologue in humans (hGC-G). By the comparative genomic approach, hGC-G gene is composed of 21 exons, spanning a minimum of 48 kb on chromosome 10q25. When compared with the mouse orthologue, hGC-G showed in the presence of deletions, incomplete splicing of introns, or in-frame termination codons. The real-time quantitative reverse transcriptase (RT)-PCR analysis demonstrated that hGC-G is expressed in human testis, followed by a low expression in placenta, but with no expression in other tissues. Western blotting revealed that hGC-G in sperm composed three isoforms ranged in 30 ~ 45 kDa, and was expressed on the cell surface of spermatozoa by utilizing flow cytometry and confocal immunofluorescent analysis. Furthermore, with hGC-G-RGD peptide and anti-hGC-G antibody neutralizing assay, we found that hGC-G may involve in molecular recognition of sperm (RGD motif of hGC-G on sperm) and oocyte (integrin on oocyte), but not in receptor-transmitted capacitation signalings.
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