Expression and characterization of the human YWK-II gene, encoding a sperm membrane protein related to the Alzheimer βA4-amyloid precursor protein

• Published in: Molecular human reproduction 2000-12, Vol.6 (12), p.1069-1078
• Main Authors: Huang, Peng, Miao, Shiying, Fan, Hongyu, Sheng, Qi, Yan, Yuanchang, Wang, Linfang, Koide, S.S.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; cell signalling; Fundamental and applied biological sciences. Psychology; G proteins; Gene expression; Molecular and cellular biology; Molecular genetics; protein kinase; sperm membrane protein; YWK-II
• ISSN: 1360-9947; 1460-2407
• DOI: 10.1093/molehr/6.12.1069

The YWK-II cDNA, RSD-2, encoding a sperm membrane protein was isolated from a rat testis cDNA expression library. Using the RSD-2 insert in combination with rapid amplification of cDNA ends (RACE), the corresponding human gene was isolated from a human testis cDNA expression library. The human testis cDNA, HSD-2, is 3654 bp in length and contains an open reading frame of 763 codons. Hydropathicity analysis showed that the deduced polypeptide is a single strand transmembrane protein. The deduced polypeptide has partial homology with the amyloid precursor protein (APP) and high homology with the amyloid precursor homologue, APLP2/APPH. The YWK-II gene was mapped and assigned to human chromosome locus: 11q24-25. Northern blotting of various human tissue RNAs using the HSD-2 cDNA as a probe showed that the gene is transcribed ubiquitously. The cytoplasmic domain of HSD-2 was expressed in Escherichia coli. In-vitro studies showed that the recombinant polypeptide bound to a GTP-binding protein (Go) and was phosphorylated by protein kinase C and cdc2 kinase. In mammalian F11 cells, the recombinant polypeptide was found to be coupled to Go. Thus, the YWK-II component has the characteristics of a Go-coupled receptor and may be involved in Go-mediated signal transduction pathway. Protein kinase C and cdc2 kinase may regulate this pathway in spermatozoa by phosphorylating the cytoplasmic domain of the YWK-II component.