Identification of 36 kDa phosphoprotein in fibrous sheath of hamster spermatozoa.

In our previous studies (Fujinoki et al., 2001, 2003), we reported that two types of 36 kDa proteins, designated 36K-A protein and 36K-B protein, obtained from hamster sperm flagella, are associated with motility activation and phosphorylated in a cAMP-dependent manner at serine residues. In the present experiments, we focused on the hamster (Mesocricetus auratus) 36K-A protein, which was analyzed by peptide mass finger printing and amino acid sequencing. The results suggest that 36K-A protein is a pyruvate dehydrogenase E1 component beta subunit lacking the N-terminal 30 amino acids. Moreover, our results suggest that 36 K-A protein is localized in the fibrous sheath of the principal piece of hamster spermatazoa.