Oviductin, the oviductal protease that mediates gamete interaction by affecting the vitelline coat in Bufo japonicus: its molecular cloning and analyses of expression and posttranslational activation.
Previous studies indicated that the acquisition of egg fertilizability during transit through the pars recta portion of the oviduct in Bufo japonicus is accompanied by hydrolytic conversion of the vitelline coat 40- to 52-kDa components to 39-kDa components induced by a 66-kDa serine protease, "oviductin." In this study, we cloned a 3028-bp cDNA that contained an open reading frame encoding 974 amino acids with a calculated molecular mass of 107.6 kDa, including two protease domains and three repeats of CUB domains. Sequence analysis indicated that the catalytically active 66-kDa protein comprised an N-terminally located oviductin protease and two CUB domains. The oviductin gene was transcribed as a part of 6-kb mRNA that was expressed specifically in the cells lining the bottom of epithelial folds in the oviductal pars recta, and this expression was highly accelerated when the pars recta fragments were cultured in the presence of hCG. Western blot analyses using antibodies against a protease domain revealed that the catalytically inactive 102-kDa proteins in the pars recta granules yield 66-kDa catalytically active and 82- and 59-kDa inactive molecules. We propose that the oviductin translated as 107.6-kDa precursors are processed both N- and C-terminally to give rise to a 66-kDa active form comprising a serine protease and two CUB domains.
Hiyoshi
Masateru
M
Department of Materials and Life Science, Graduate School of Science and Technology, Kumamoto University, Japan.
Takamune
Kazufumi
K
Mita
Koichi
K
Kubo
Hideo
H
Sugimoto
Yasusi
Y
Katagiri
Chiaki
C
D000595:Amino Acid Sequence; D000818:Animals; D002025:Bufonidae / Q000502:physiology*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000032:analysis / Q000235:genetics; D005260:Female; D008969:Molecular Sequence Data; D010057:Oviducts / Q000502:physiology*; D010063:Ovum / Q000502:physiology; D011499:Protein Processing, Post-Translational; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D016415:Sequence Alignment; D012697:Serine Endopeptidases / Q000235:genetics* / Q000378:metabolism* / Q000502:physiology; D014816:Vitelline Duct / Q000502:physiology
D018076:DNA, Complementary; D012333:RNA, Messenger; D012697:Serine Endopeptidases; C074599:oviductin