G-protein-mediated signal transduction for meiosis reinitiation in starfish oocyte

Starfish oocyte maturation is induced by 1-methyladenine. There were apparently two forms of 1-methyladenine receptor affected by GTP gamma S. Pertussis toxin ADP-ribosylated the 39-kDa alpha subunit of a G protein and inhibited maturation. Also, the G protein was ADP-ribosylated by cholera toxin only when 1-methyladenine was added. The purified G protein had an heterotrimeric structure consisting of 39 kDa alpha, 37 kDa beta, and 8 kDa gamma subunits. The deduced amino acid sequence of the cDNA of starfish G alpha was 89% identical to mammalian Gi-1 alpha. The purified starfish beta gamma-subunits induced maturation when they were microinjected into oocytes.