Cloning and characterization of SOB1, a new testis-specific cDNA encoding a human sperm protein probably involved in oocyte recognition

A human sperm-oocyte binding protein, SOB1, was purified by two dimensional gel electrophoresis and sequenced. This protein was selected because it wa s recognized by a monoclonal antibody that inhibited the binding of human s perm to zona-free hamster oocytes. The sequences of the tryptic peptides we re used to design degenerate primers. These were used to amplify a specific fragment from human testis cDNA by the polymerase chain reaction. This 123 3 bp fragment was extended in 3' and 5' by RACE to obtain the 3 kb full len gth SOB1 cDNA, Sequence analysis indicated that the deduced open reading fr ame encodes a 853 amino acid protein, with a molecular mass of 94.7 kDa. Th is is a new testis-specific cDNA. It is 27, 32.8 and 34.4% homologous to th ree sperm proteins, HI, Fsc1 and AKAP82 respectively. A single 3kb transcri pt was demonstrated only in the testis by northern blot analysis. It is a s ingle copy gene, well conserved among mammals and located on human chromoso me 12 at band p13. (C) 1999 Academic Press.