title: The calcium loading of secretory granules. A possible key event in stimulus-secretion coupling.
abstract: The review focuses on calcium accumulation by secretory organelles. The observation that secretory granules contain variable and often important quantities of calcium (1-200 mM of total calcium) can be interpreted as a maturation index. A progressive loading with calcium would be permitted by a Ca2(+)-transport mechanism on the granular membrane and calcium-binding molecules in the granular core. The saturation of this store by the stimulus-induced calcium transient would permit in mature (calcium-loaded) granules the ionic crisis leading to exocytosis. The inside of secretory organelles being acidic, calcium influx into the granule can be driven by calcium-proton exchange. The calcium-proton exchanger could be a Ca2(+)-ATPase.
authors.affiliation: Laboratoire de Physiologie Cellulaire et Comparée, Université de Nice-Sophia Antipolis, Nice, France.
authors.forename: G
authors.initials: G
authors.lastname: Nicaise
authors.forename: K
authors.initials: K
authors.lastname: Maggio
authors.forename: S
authors.initials: S
authors.lastname: Thirion
authors.forename: M
authors.initials: M
authors.lastname: Horoyan
authors.forename: E
authors.initials: E
authors.lastname: Keicher
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003594:Cytoplasmic Granules / Q000378:metabolism*; D006801:Humans
chemical_list: D002118:Calcium