Hormonal control of meiosis: specificity of the 1-methyladenine receptors in starfish oocytes.

Abstract

The specificity of the 1-methyladenine [1-MeAde] receptors localized on the cell membrane of starfish oocytes, was investigated in Marthasterias glacialis and Asterias rubens. Ability of N1-substituted adenines to trigger the release of meiosis inhibition is conserved, or even increased, when the methyl group is replaced by larger substituent groups. 1-MeAde very likely binds to its receptors in the N9 or N7-N9 region, as suggested by the loss of activity of 1-MeAde when this compound is further substituted at N9 or N7, and by the remaining ability of N1,N6-disubstituted adenines to trigger the meiosis program. Because 1-alkyl-substituted adenines exist .apprx. 50% in the protonated form at pH 7, a further requirement of the receptor appears to be a cationic center in the pyrimidine ring of the hormone or its analogs. The duration of the hormone-dependent period (.apprx. 5 min) depends only slightly on the nature of the active compound used.