Role Of The Yeast Two-hybrid System To Screen A Human Sperm Membrane Protein Ywk-ii Protein Extracellular Area Ligand

Sperm membrane proteins play an important role in fertilization and in spermatogenesis. In a previous study, a novel membrane protein of human sperm, designated as YWK-II was isolated and characterized. Its open reading frame consists of 763 codons encoding a polypeptide characteristic of a single transmembrane protein established by hydropathicity analysis. Although the YWK-II gene has 70% homology to that of Alzheimer amyloid precursor protein (APP) within the transmembrane and cytoplasmic domains, the extracellular domain of YWK-II and is distinctly different from that of APP and is shown to possess an antifertility activity. Recent inquiry into the molecular basis of the function of YWK-II peptide revealed that its cytoplasmic domain binds specifically to GTP-binding protein, Go , suggesting that this sperm component may act by coupling to G proteins thereby activating the signal transduction system of responsive cells.To determine the function of YWK-II, a yeast two-hybrid system was used in screening a mouse testis cDNA library and rat ovary cDNA library to identify potential ligands that can interact with the extracellular domain of this sperm protein. This methods was established on the facts that the non-covalent interaction between two proteins can bring the activation domain of an eukaryotic trans-acting factors in close proximity to its DNA binding domain, thus reconstitute a functional...