Cloning and partial characterization of the cDNA encoding the fox sperm protein FSA-Acr.1 with similarities to the SP-10 antigen.

We have isolated and characterized a cDNA, cFSA-Acr.1, encoding a testis-specific fox sperm antigen. The antigen is located on the inner acrosomal compartment, and is expressed during spermatogenesis on the developing acrosome of round and elongating spermatids. Database searches with the deduced amino acid sequence of cFSA-Acr.1 revealed that the clone has high homology to both human and baboon sperm protein SP-10, and the mouse sperm protein, MSA-63. The region of highest homology is within the carboxyl terminus. In the middle of the open reading frame, the fox sequence shows unique sequences absent from both the human, baboon SP-10, and mouse MSA-63 sequences. In addition to cFSA-Acr.1, two other clones were also isolated from the same fox testis cDNA library, and sequence analysis shows that they may represent alternatively spliced mRNAs coding for other FSA-Acr proteins.