Expression of c-mos protein in cultured rat spermatogenic cells and evidence that rat testicular 43 kDa c-mos protein has an elongated amino acid sequence at the N-terminus

• Published in: Biochimica et biophysica acta 1995-08, Vol.1245 (1), p.130-143
• Main Author: Nagao, Yosinobu
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Amino Acids - analysis; Animals; c-mos; Cell culture; Cell Cycle; Cells, Cultured; Chromatography, Gel; Chromatography, High Pressure Liquid; Glycosylation; Isoelectric Focusing; Male; Molecular Sequence Data; Phosphorylation; Protein Biosynthesis; Proto-oncogene; Proto-Oncogene Proteins c-mos - biosynthesis; Proto-Oncogene Proteins c-mos - genetics; Proto-Oncogene Proteins c-mos - isolation & purification; Rats; Serine phosphorylation; Spermatogenesis; Spermatozoa - metabolism; Testis - growth & development; Testis - metabolism; Translation
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/0304-4165(94)00185-Z

Expression of c-mos protein in rat spermatogenesis was examined by means of a cell culture system. A commercially available antibody (Cambridge Research Biochemicals, OA-11-861) was used to detect the protein. The 43 kDa c-mos (43K c-mos) protein was detectable in spermatogenic cells close to the occurrence of the first meiotic divisions (a few days before appearance of spermatids) during postnatal development, which was nearly consistent with expression in vivo. The results suggested that the c-mos protein has a role in meiotic maturation of spermatogenic cells. The 43K c-mos protein was partially purified from rat testes and the protein band was identified. The 43K c-mos protein had a p I value of around 9.0–9.6 having a hydrophobic nature, and was phosphorylated in vitro on serine. Neither ubiquitination nor glycosylation were detected. N-Terminal amino acid sequencing showed that the 43K c-mos protein has a Asp-Glu-Gly-Gly-Asn-Leu-Gln-sequence located 5′ upstream (99 bases upstream) of the rat c-mos coding sequence reported. The amino acid analysis revealed a nearly consistent composition with that deduced from the DNA sequence. These results suggested that rat testicular 43K c-mos protein is translated from a 5′ upstream sequence of the predicted consensus AUG start codon, probably by an unusual translational rule.