Induction of starfish oocyte maturation by the beta gamma subunit of starfish G protein and possible existence of the subsequent effector in cytoplasm.
beta gamma subunits of G proteins were purified from starfish oocytes, and their role in the induction of oocyte maturation by 1-methyladenine was investigated. When injected into starfish oocytes, the purified beta gamma subunit of the starfish G protein induced germinal vesicle breakdown (GVBD) faster than that of bovine brain G protein. Injection of the starfish beta gamma into cytoplasm near the germinal vesicle (GV) induced GVBD earlier than when injected into the GV or the cytoplasm near the plasma membrane. Fluorescent-labeled beta gamma was retained in the injected area even after GVBD. Injected beta gamma also induced the formation of maturation-promoting factor as well as an increase of histone H1 kinase activity. These results suggest that beta gamma dissociates from alpha-subunit by the stimulation of 1-methyladenine and interacts with a cytoplasmic effector, which results in formation of active cdc2 kinase.
Chiba
K
K
Department of Life Science, Tokyo Institute of Technology, Yokohama, Japan.
Kontani
K
K
Tadenuma
H
H
Katada
T
T
Hoshi
M
M
D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001923:Brain Chemistry; D002417:Cattle; D003593:Cytoplasm / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000502:physiology*; D007447:Invertebrate Hormones / Q000494:pharmacology; D016200:Maturation-Promoting Factor / Q000032:analysis / Q000502:physiology; D008845:Microinjections; D009685:Nuclear Envelope / Q000378:metabolism; D009865:Oocytes / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D006656:Protamine Kinase / Q000032:analysis; D013215:Starfish / Q000502:physiology*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D007447:Invertebrate Hormones; D010566:Virulence Factors, Bordetella; C008407:1-methyladenine; D006656:Protamine Kinase; D016200:Maturation-Promoting Factor; D019204:GTP-Binding Proteins; D000225:Adenine