title: CAPS facilitates filling of the rapidly releasable pool of large dense-core vesicles.
abstract: 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.
authors.affiliation: Institut für Physiologie, Universität des Saarlandes, D-66421 Homburg/Saar, Germany.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Liu
authors.forename: Claudia
authors.initials: C
authors.lastname: Schirra
authors.forename: David R
authors.initials: DR
authors.lastname: Stevens
authors.forename: Ulf
authors.initials: U
authors.lastname: Matti
authors.forename: Dina
authors.initials: D
authors.lastname: Speidel
authors.forename: Detlef
authors.initials: D
authors.lastname: Hof
authors.forename: Dieter
authors.initials: D
authors.lastname: Bruns
authors.forename: Nils
authors.initials: N
authors.lastname: Brose
authors.forename: Jens
authors.initials: J
authors.lastname: Rettig
mesh_terms: 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
chemical_list: 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