SEQUENCE AND CHARACTERIZATION OF THE SPERM PROTEIN SP17 FROM THE BABOON

In this study, cDNAs encoding the sperm protein Sp17 from the baboon ( Papio papio) have been cloned and sequenced. Three clones, differing i n the lengths of their 3' untranslated regions, were identified, which were encoded by mRNA transcripts of 0.8-1.35 kb. The open reading fra me encodes 163 amino acids with a predicted molecular mass of 18.8 kDa . The baboon Sp17 protein sequence is 97% identical to human Sp17 but differs significantly by the addition of 12 amino acids at the C-termi nal, providing an additional potential protein kinase C phosphorylatio n site. Northern blot analysis demonstrated that the baboon Sp17 mRNA was specific to the baboon testes and was not detected in the ovary, p lacenta, or any of the other somatic tissues tested. Western blot anal ysis using anti-Sp17 antibodies demonstrated that the native baboon sp erm Sp17 protein consists-of a doublet with an apparent M-r of 26.5 an d 27.2 kDa, Immunocytochemical staining of baboon testis with anti-Sp1 7 antibodies demonstrated Sp17 in spermatocytes, spermatids, and sperm atozoa. within the seminiferous epithelium, No specific staining was o bserved on spermatogonia. Sertoli cells, Leydig cells, or other somati c cell types. (C) 1997 Wiley-Liss, Inc.