Identification of a novel substrate for tyrosine kinase in human testes

Identification of genes specifically expressed in adult and fetal testes is important in furthering our understanding of testis development and function. In this study, a novel human specific transcript, designated NYD-SP10, was identified by hybridization of adult and fetal human testis probes with a human cDNA microarray. NYD-SP10 (GenBank Accession no. AF332192) was expressed at a higher level in adult testes than in fetal testes. Bioinformatic analysis illustrated NYD-SP10 is a splice variant of regulatory factor X4, while it is lack of RFX DNA-binding domain which binds to the X box of MHC class II genes. Most telling of all, NYD-SP10 uniquely possesses a tyrosine kinase phosphorylation site. Expression profiles demonstrated NYD-SP10 is specifically and strongly expressed in human adult testes and ejaculated spermatozoa. Taken together, these results suggest that NYD-SP10 is a novel testis-specific gene and it is possibly a novel substrate for tyrosine kinase and involved in the function of human spermatozoa, especially during capacitation.