TY - JOUR
T1 - Pertussis toxin-sensitive G protein participating in starfish oocyte maturation induced by 1-methyladenine
AU - Hoshi, Motonori
AU - Chiba, Kazuyoshi
AU - Matsumoto, Midori
AU - Tadenuma, Hirohiko
AU - Takahashi, Katsunobu
AU - Katada, Toshiaki
N1 - Funding Information:
This work was supported in part by Grants-in-Aid for Scientific Research on Priority Areas (to M.H. and T.K.) and for General Scientific Research (to M.H.) from the Ministry of Education, Science and Culture of Japan, the Human Frontier Science Pro- gram (to T.K.), and the Cooperative Program provid-ed by Ocean Research Institute, University of Tokyo (to M.H.).
PY - 1992/12
Y1 - 1992/12
N2 - 1-Methyladenine (1-MA) secreted from the follicle cells is the biological signal for meiosis reinitiation of starfish oocytes. The signal of 1-MA is transduced into cytoplasmic formation of maturation-promoting factor (MPF) that eventually induces a germinal vesicle breakdown (GVBD). Microinjection of pertussis toxin (PTX) inhibited 1-MA-induced GVBD in Asterina pectinifera and Asterina (Patiria) miniata. PTX-inhibition of GVBD was rescued by the injection of MPF into PTX-preinjected oocytes. Most of the PTX-and MPF-double injected eggs were fertilized and underwent cleavage, suggesting the presence of a GTP-binding protein (G protein) specific for 1-MA signal transduction. Indeed, plasma membrane preparations of A. pectinifera oocytes contained a G protein consisting of 39-kDa α, 37-kDa β, and 8-kDa γ subunits. The a subunit contained a site for ADP-ribosylation catalyzed by PTX. It was also recognized by antibodies specific for a common GTP-binding site of mammalian a subunits or a carboxy-terminal ADP-ribosylation site of mammalian inhibitory G protein (Gi) α subunits. Its gene was 74% and 83.7% identical to the rat Gi-2α gene in nucleotide and deduced amino acid sequences, respectively. The 39-kDa α subunit shared the common GTP-binding site of mammalian G protein a subunits and the PTX-catalyzed ADP-ribosylation site of mammalian Giα subunits as expected from the immunoreactivity. The oocyte membranes had apparently two forms of 1-MA receptors with high and low affinities. The high-affinity form was converted into the low-affinity one in the presence of a non-hydrolyzable analogue of GTP. The 39-kDa α subunit of starfish G protein was also ADP-ribosylated by cholera toxin only when 1-MA was added to the membranes. These results indicate that in starfish oocyte membranes, 1-MA receptors are functionally coupled with the 39-kDa PTX-substrate G protein that transduces the signal into the formation of a cytoplasmic factor (MPF) and eventually into the reinitiation of meiosis.
AB - 1-Methyladenine (1-MA) secreted from the follicle cells is the biological signal for meiosis reinitiation of starfish oocytes. The signal of 1-MA is transduced into cytoplasmic formation of maturation-promoting factor (MPF) that eventually induces a germinal vesicle breakdown (GVBD). Microinjection of pertussis toxin (PTX) inhibited 1-MA-induced GVBD in Asterina pectinifera and Asterina (Patiria) miniata. PTX-inhibition of GVBD was rescued by the injection of MPF into PTX-preinjected oocytes. Most of the PTX-and MPF-double injected eggs were fertilized and underwent cleavage, suggesting the presence of a GTP-binding protein (G protein) specific for 1-MA signal transduction. Indeed, plasma membrane preparations of A. pectinifera oocytes contained a G protein consisting of 39-kDa α, 37-kDa β, and 8-kDa γ subunits. The a subunit contained a site for ADP-ribosylation catalyzed by PTX. It was also recognized by antibodies specific for a common GTP-binding site of mammalian a subunits or a carboxy-terminal ADP-ribosylation site of mammalian inhibitory G protein (Gi) α subunits. Its gene was 74% and 83.7% identical to the rat Gi-2α gene in nucleotide and deduced amino acid sequences, respectively. The 39-kDa α subunit shared the common GTP-binding site of mammalian G protein a subunits and the PTX-catalyzed ADP-ribosylation site of mammalian Giα subunits as expected from the immunoreactivity. The oocyte membranes had apparently two forms of 1-MA receptors with high and low affinities. The high-affinity form was converted into the low-affinity one in the presence of a non-hydrolyzable analogue of GTP. The 39-kDa α subunit of starfish G protein was also ADP-ribosylated by cholera toxin only when 1-MA was added to the membranes. These results indicate that in starfish oocyte membranes, 1-MA receptors are functionally coupled with the 39-kDa PTX-substrate G protein that transduces the signal into the formation of a cytoplasmic factor (MPF) and eventually into the reinitiation of meiosis.
KW - 1-methyladenine
KW - Asterina pectinifera
KW - G protein
KW - Oocyte maturation
KW - Pertussis toxin
KW - Signal transduction
KW - Starfish
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U2 - 10.1080/07924259.1992.9672250
DO - 10.1080/07924259.1992.9672250
M3 - Article
AN - SCOPUS:0003950431
SN - 0792-4259
VL - 22
SP - 1
EP - 10
JO - Invertebrate Reproduction and Development
JF - Invertebrate Reproduction and Development
IS - 1-3
ER -
