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DEFINITIVE EXPRESSION OF C‐MOS IN LATE MEIOTIC PROPHASE LEADS TO PHOSPHORYLATION OF A 34KDA PROTEIN IN CULTURED RAT SPERMATOCYTES
Author(s) -
Nagao Yosinobu
Publication year - 2002
Publication title -
cell biology international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 77
eISSN - 1095-8355
pISSN - 1065-6995
DOI - 10.1006/cbir.2001.0834
Subject(s) - prophase , cyclin dependent kinase 1 , phosphorylation , kinase , protein kinase a , meiosis , biology , microbiology and biotechnology , mapk/erk pathway , spermatogenesis , mitogen activated protein kinase , signal transduction , cell cycle , cell , biochemistry , endocrinology , gene
To investigate the role of c‐mos in rat spermatogenesis, expression of c‐mos, MAP kinase kinase (MAPKK), MAP kinase (MAPK), cdc2 and protein kinase A (PKA) by spermatogenic cell culture of 14 day‐old rats was examined. MAPKK and PKA expressions were constitutive, whereas the expression of MAPK and cdc2 in spermatogonia initially decreased, but later increased on meiotic maturation of spermatocytes. c‐mos expression was definitive of late meiotic prophase. c‐mos immunoprecipitates prepared from the c‐mos‐enriched fraction (pI9.0–9.6) could form complex(es) in the cultured spermatogenic cell lysates. In vitro phosphorylation of the c‐mos immune complexes revealed a 34 kDa protein that was phosphorylated at serine and threonine residues as a target of the c‐mos signal. Its pI value was 4.4–4.5, and cdc2 was not detected, making it different from cdc2 (p34). These results suggest that the phosphorylation of the 34kDa protein by the c‐mos signal may play a crucial role in the meiotic division of rat spermatocytes.