Identification and characterization of P31m, a novel sperm protein in Cynomolgus monkey (Macaca fascicularis)

We have previously described a hamster sperm glycoprotein, P26h, which is i mplicated in the cascade of events occurring during the interaction between mature spermatozoa and the oocyte's zona pellucida. The P26h is acquired o n the acrosomal cap of the spermatozoon during its maturation arising withi n the epididymis. Lately, using a polyclonal antiserum raised against P26h, a 34 kDa protein, P34H, has been identified on the acrosomal cap of the hu man spermatozoon. The cloning and sequencing of the cDNA encoding P34H has revealed a 65% similarity between the P34H and P26h amino acid sequences. C onsidering that P26h shows total immunocontraceptive properties in the hams ter, it is of relevant importance to have an animal model phylogenetically closer to the human. Using the Cynomolgus monkey, we searched for a protein autologous to the human P34H. A 31 kDa protein, the P31m, localized on the acrosomal cap of the monkey spermatozoon has been identified by a Western blot analysis and by immunohistochemical techniques using an anti-hamster P 26h antiserum. Northern blot analysis showed increasing high levels of the P31m mRNA through the epididymis and at lower levels in the testis. In situ hybridization showed the presence of the P31m mRNA in the principal cells of the epididymis. The cloning and sequencing of the cDNA encoding the P31m showed a high homology of 97% identity between the P31m and P34H nucleotid ic sequences. This study clearly demonstrates that the monkey P31m is the h omologous protein of the hamster P26h and of the human P34H. (C) 2001 Wiley -Liss, Inc.