title: Calcineurin: a calcium- and calmodulin-binding protein of the nervous system.
abstract: The inhibitory protein that binds calmodulin and thus prevents activation of several Ca2+-dependent enzymes by calmodulin is shown to also bind four Ca2+ per mol of protein with high affinity (Kd less than or equal to 10(-6) M). On the basis of its Ca2+- binding properties and its localization to nervous tissue, the inhibitory protein is now called "calcineurin." Calcineurin is composed of two subunits: calcineurin A (61,000 Mr) which interacts with calmodulin in a Ca2+-dependent fashion, and calcineurin B (15,000 Mr) which binds Ca2+. The interaction of calcineurin A with calcineurin B is independent of Ca2+ or Mg2+. The dual interaction of calcineurin A with two different Ca2+-binding components and the high affinity of calcineurin for Ca2+ suggest a possible role for calcineurin in the regulation of free Ca2+ concentrations in the nervous system. Calcineurin may thereby modulate the release and action of neurotransmitters.
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism*; D002417:Cattle; D008970:Molecular Weight; D009419:Nerve Tissue Proteins / Q000302:isolation & purification / Q000378:metabolism*; D011485:Protein Binding
chemical_list: D002135:Calcium-Binding Proteins; D002147:Calmodulin; D009419:Nerve Tissue Proteins; D002118:Calcium