NAADP mobilizes Ca(2+) from reserve granules, lysosome-related organelles, in sea urchin eggs

Cell. 2002 Nov 27;111(5):703-8. doi: 10.1016/s0092-8674(02)01082-6.


Nicotinic acid adenine dinucleotide phosphate (NAADP) mobilizes Ca(2+) in many cells and species. Unlike other Ca(2+)-mobilizing messengers, NAADP mobilizes Ca(2+) from an unknown store that is not the endoplasmic reticulum, the store traditionally associated with messenger-mediated Ca(2+) signaling. Here, we demonstrate the presence of a Ca(2+) store in sea urchin eggs mobilized by NAADP that is dependent on a proton gradient maintained by an ATP-dependent vacuolar-type proton pump. Moreover, we provide pharmacological and biochemical evidence that this Ca(2+) store is the reserve granule, the functional equivalent of a lysosome in the sea urchin egg. These findings represent an unsuspected mechanism for messenger-mediated Ca(2+) release from lysosome-related organelles.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Calcium Signaling / drug effects
  • Cytoplasmic Granules / drug effects
  • Cytoplasmic Granules / metabolism*
  • Female
  • Lysosomes / metabolism*
  • Models, Biological
  • NADP / analogs & derivatives*
  • NADP / metabolism*
  • NADP / pharmacology
  • Organelles / metabolism*
  • Ovum / cytology
  • Ovum / metabolism*
  • Proton Pumps
  • Sea Urchins


  • Proton Pumps
  • NADP
  • Calcium