title: Calciosome, a sarcoplasmic reticulum-like organelle involved in intracellular Ca2+-handling by non-muscle cells: studies in human neutrophils and HL-60 cells.
abstract: Calciosomes are intracellular organelles in HL-60 cells, neutrophils and various other cell types, characterized by their content of a Ca2+-binding protein that is biochemically and immunologically similar to calsequestrin (CS) from muscle cells. In subcellular fractionation studies the CS-like protein copurifies with functional markers of the inositol 1,4,5-trisphosphate (IP3) releasable Ca2+-store. These markers (ATP-dependent Ca2+-uptake and IP3-induced Ca2+-release) show a subcellular distribution which is clearly distinct from the endoplasmic reticulum and other organelles. In morphological studies, antibodies against rabbit skeletal muscle CS protein specifically stained hitherto unrecognized vesicles with a diameter between 50 and 250 nm. Thus both, biochemical and morphological studies indicate that the calsequestrin containing intracellular Ca2+-store, now referred to as the calciosome, is distinct from other known organelles such as endoplasmic reticulum. Calciosomes are likely to play an important role in intracellular Ca2+-homeostasis. They are possibly the intracellular target of inositol 1,4,5-trisphosphate and thus the source of Ca2+ that is redistributed into the cytosol following surface receptor activation in non-muscle cells.
authors.affiliation: Division of Infectious Diseases, Hôpital Cantonal Universitaire, Geneva, Switzerland.
authors.forename: K H
authors.initials: KH
authors.lastname: Krause
authors.forename: D
authors.initials: D
authors.lastname: Pittet
authors.forename: P
authors.initials: P
authors.lastname: Volpe
authors.forename: T
authors.initials: T
authors.lastname: Pozzan
authors.forename: J
authors.initials: J
authors.lastname: Meldolesi
authors.forename: D P
authors.initials: DP
authors.lastname: Lew
mesh_terms: D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D002155:Calsequestrin / Q000378:metabolism; D002460:Cell Line; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000502:physiology; D009504:Neutrophils / Q000378:metabolism* / Q000648:ultrastructure; D015388:Organelles / Q000145:classification / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*
chemical_list: D015220:Calcium Channels; D002135:Calcium-Binding Proteins; D002155:Calsequestrin; D007295:Inositol Phosphates; D015544:Inositol 1,4,5-Trisphosphate; D000252:Calcium-Transporting ATPases; D002118:Calcium