Unique inactivation properties of NAADP-sensitive Ca2+ release.
Ca2+ mobilization from intracellular stores constitutes an important mechanism for generating cytoplasmic Ca2+ signals. Inositol trisphosphate (InsP3) and ryanodine receptors are the two families of intracellular Ca2+ release channels that have been identified, which may be regulated by separate intracellular messengers, InsP3, and cyclic adenosine 5'-diphosphate ribose, respectively. A third molecule, nicotinic acid adenine dinucleotide phosphate (NAADP), has recently been recognized as a potent Ca2+ releasing agent in sea urchin eggs and microsomes. We now report that non-releasing concentrations of NAADP fully and irreversibly inactivate the NAADP-sensitive Ca2+ release mechanism. This phenomenon occurred both in intact sea urchin eggs and in homogenates and is not shared by either InsP3 or cyclic adenosine 5'-diphosphate ribose. The novel properties of this Ca2+ release mechanism, giving a one-shot Ca2+ release, may be suited to irreversible cellular events.
Genazzani
A A
AA
Department of Pharmacology, University of Oxford, United Kingdom.
Empson
R M
RM
Galione
A
A
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D005260:Female; D009249:NADP / Q000031:analogs & derivatives* / Q000494:pharmacology; D010063:Ovum / Q000378:metabolism; D012617:Sea Urchins
D009249:NADP; C024376:NAADP; D002118:Calcium