Emptying of intracellular Ca2+ stores releases a novel small messenger that stimulates Ca2+ influx.
Intracellular Ca2+ signals that last more than a few minutes after the onset of stimulation depend critically on influx of extracellular Ca2+. Such Ca2+ influx can be triggered in many cell types by depletion of intracellular Ca2+ stores without detectable elevations of known messengers. The mechanism by which store depletion can control plasma membrane Ca2+ permeability remains controversial. Here we present evidence for a novel soluble mediator. Calcium depletion of a lymphocyte cell line caused the messenger to be released from intracellular organelles into the cytoplasm and to a much lesser extent into the extracellular medium. The messenger caused Ca2+ influx when applied to macrophages, astrocytoma cells, and fibroblasts and was therefore named CIF (for Ca(2+)-influx factor). CIF appears to have hydroxyls (or hydroxyl and amino groups) on adjacent carbons, a phosphate, and a M(r) under 500.
Randriamampita
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Department of Pharmacology, University of California, San Diego, La Jolla 92093-0647.
Tsien
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RY
D001254:Astrocytoma; D001685:Biological Factors / Q000737:chemistry / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D005227:Fatty Acids / Q000494:pharmacology; D005347:Fibroblasts; D006593:Hexokinase / Q000494:pharmacology; D006801:Humans; D008264:Macrophages; D015388:Organelles / Q000378:metabolism; D010835:Phytohemagglutinins / Q000494:pharmacology; D015290:Second Messenger Systems; D012710:Serum Albumin, Bovine / Q000494:pharmacology; D013601:T-Lymphocytes; D014407:Tumor Cells, Cultured
D001685:Biological Factors; D005227:Fatty Acids; D010835:Phytohemagglutinins; D012710:Serum Albumin, Bovine; D006593:Hexokinase; D002118:Calcium