Expression of a sperm protein gene during spermatogenesis in mammalian testis: an in situ hybridization study.

In previous work a specific membrane protein with an estimated Mr of 20.1 kDa was purified from rabbit sperm tails and designated as rSMP-B protein. Antibodies were raised against rSMP-B protein and used to isolate and identify the cDNA coding the rSMP-B protein from a rat testis lambda gt11 expression library. The nucleotide sequence of the cDNA was determined in a previous study. Single-stranded 35S-labeled RNA probes were prepared. With the techniques of in situ hybridization, rSMP-B mRNA was detected in spermatids of rat and rabbit testis. The present results support our previous observation that immunization of male rabbits with the rSMP-B protein results in the arrest of spermatogenesis at the spermatid stage. Overall, rSMP-B protein appears to be involved in spermiogenesis, and the synthesis of the mRNA encoding the protein occurs in germ cells during the postmeiotic haploid phase of spermatogenesis.