CAPS facilitates filling of the rapidly releasable pool of large dense-core vesicles.
Calcium-activator protein for secretion (CAPS) is a cytosolic protein that associates with large dense-core vesicles and is involved in their secretion. Mammals express two CAPS isoforms, which share a similar domain structure including a Munc13 homology domain that is believed to be involved in the priming of secretory vesicles. A variety of studies designed to perturb CAPS function indicate that CAPS is involved in the secretion of large dense-core vesicles, but where in the secretory pathway CAPS acts is still under debate. Mice in which one allele of the CAPS-1 gene is deleted exhibit a deficit in catecholamine secretion from chromaffin cells. We have examined catecholamine secretion from chromaffin cells in which both CAPS genes were deleted and show that the deletion of both CAPS isoforms causes a strong reduction in the pool of rapidly releasable chromaffin granules and of sustained release during ongoing stimulation. We conclude that CAPS is required for the adequate refilling and/or maintenance of a rapidly releasable granule pool.
Liu
Yuanyuan
Y
Institut für Physiologie, Universität des Saarlandes, D-66421 Homburg/Saar, Germany.
Schirra
Claudia
C
Stevens
David R
DR
Matti
Ulf
U
Speidel
Dina
D
Hof
Detlef
D
Bruns
Dieter
D
Brose
Nils
N
Rettig
Jens
J
D000311:Adrenal Glands / Q000166:cytology; D000818:Animals; D001692:Biological Transport / Q000235:genetics / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects; D002135:Calcium-Binding Proteins / Q000172:deficiency / Q000502:physiology*; D002395:Catecholamines / Q000378:metabolism; D002478:Cells, Cultured; D019439:Chromaffin Cells / Q000648:ultrastructure*; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D004622:Embryo, Mammalian; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D051379:Mice; D018345:Mice, Knockout; D046529:Microscopy, Electron, Transmission / Q000379:methods; D009419:Nerve Tissue Proteins / Q000172:deficiency / Q000502:physiology*; D018408:Patch-Clamp Techniques; D010782:Photolysis; D022142:Secretory Vesicles / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D014162:Transfection / Q000379:methods
C480975:CAPS2 protein, mouse; C510820:Cadps protein, mouse; D002135:Calcium-Binding Proteins; D002395:Catecholamines; D009419:Nerve Tissue Proteins; D049452:Green Fluorescent Proteins; C085112:2-nitrophenyl-EGTA; D004533:Egtazic Acid; D002118:Calcium