Encoding Human Sperm Membrane Protein Ywk-ii Gene

Many cDNAs encoding sperm membrane proteins as well as other proteins involved in spermatogenesis have been studied. The transcription and translation of these genes in testis reveals complexity due to the spatial and temporal regulation of these genes by both hormonal and paracrinc factors.Since 1985, our laboratory has cloned several sperm membrane protein cDNAs. One of them, designated as RSD2, was obtained after we screened rat testis λ gt11 cDNA expression library using a monoclonal antibody YWK-II against a sperm membrane protein. Sequence analysis of RSD2 showed it encoded a transmembrane protein that shared high homology with Alzheimer Disease Protein Precursor (APP). It was a receptor-like protein with a large extracellular region, a single transmembranc domain and a short intracelullar region. The function of the predicted protein was unknown. Consequently, RSD2 cDNA was utilized as a probe to screen human testis λ gt11 cDNA library and several positive clones were obtained. They were named HSD2-7, 921, 721, and 1062, etc. Two of them, HSD2-7 and 921, were sequenced and demonstrated homology and heterology. This suggested there would be variants of this mRNA in the testis. The present study is based upon these previous work to pursue further studies on these cDNAs. First, to probe any changes in the other two cDNAs, 721 (1.9kb in length), and 1062 (1.9kb in length), both the nucleotide sequences were determined. By homology comparision, we found the clone 721 has a 189bp deletion in the extrcellular region, and both 721 and 1062 have a 230bp heterogeneous region compared with 921 in the 3' untranslational rcgion(3'-UTR).Since all the four cDNAs from the testis were 5'-end truncated, aimed at getting the 5' completed sequence, HSD2-7 5'-end 500bp were labeled to screening human testis λ gt10 5'-stretch cDNA library. A 4kb cDNA designated as C211 is obtained and sequences analysis showed it is another variant of the mRNA, for C211 owns a 5' 1.8kb unique region which seems an noncoding region after the ORF searching using...