Homeostatic tuning of Ca2+ signal transduction by members of the calpacitin protein family.
The calpacitin protein family is made up of small, abundantly expressed proteins that bind to the Ca(2+)-free form of calmodulin (CaM) with an affinity equal to or greater than that of the Ca(2+)-containing form. Their CaM-binding domains are homologous and contain an IQ motif. Two members of this family, growth-associated protein-43 (GAP-43) and RC3, have been implicated in long-term potentiation (LTP) and the elaboration of pre- and postsynaptic structures. Computer-aided modeling of calpacitin-CaM interactions suggests that these molecules regulate Ca2+ flux size and CaM availability. Simulation of the interactions between the calpacitins CaM and Ca2+ imply that GAP-43 and RC3 tune and homeostatically constrain the Ca2+ signal transduction system. In so doing, they link Ca2+ fluxes to downstream elements of a signaling cascade that generates LTP.
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Department of Molecular Biology, The Scripps Research Institute, La Jolla, California 92037, USA. gerendas@scripps.edu
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism; D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D019922:GAP-43 Protein / Q000378:metabolism; D006706:Homeostasis; D006801:Humans; D017774:Long-Term Potentiation / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D051579:Neurogranin; D015398:Signal Transduction / Q000502:physiology*
D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D019922:GAP-43 Protein; C496649:NRGN protein, human; D009419:Nerve Tissue Proteins; D051579:Neurogranin; D002118:Calcium