Interaction of N1-substituted adenines with 1-methyladenine receptors of starfish oocytes in induction of maturation. 2001
Starfish oocytes are arrested naturally in the late G(2) phase of the first meiotic division. In response to the natural maturation-inducing hormone, 1-methyladenine (1-MA), oocytes undergo reinitiation of meiosis with germinal vesicle breakdown. We tested 10 newly synthesized N1-substituted adenines that are 1-MA analogues to analyze the interaction between 1-MA and its stereo-specific receptors on the oocyte plasma membranes of the starfish Asterina pectinifera. Among these analogues, 1-(beta-naphthylmethyl)adenine, 1-aminoadenine and 1-(p-nitrobenzyl)adenine played agonistic roles in the induction of oocyte maturation. 1-(o-Nitrobenzyl)adenine, 1-(m-nitrobenzyl)adenine, 1-phenethyladenine and 1-(p-nitrophenethyl)adenine had antagonist effects on 1-MA-induced oocyte maturation. These agonists and antagonists behaved competitively in the binding of [3H]1-MA to receptors in oocyte cortices. In contrast, 1-(alpha-naphthylmethyl)adenine, 1-(2,4-dinitrobenzyl)adenine and 1-(p-methoxybenzyl)adenine had no effects on oocyte maturation. Our results suggest that regional-specific sterical structures at the N1-site of adenine are important in the interaction between 1-MA and its receptors in oocytes. In addition, a negative charge at the N1-site of adenine is required for binding with the receptors.