3ox6
From Proteopedia
Crystal Structure of the calcium sensor calcium-binding protein 1 (CaBP1)
Structural highlights
Function[CABP1_HUMAN] Modulates calcium-dependent activity of inositol 1,4,5-triphosphate receptors (ITPRs). Inhibits agonist-induced intracellular calcium signaling. Enhances inactivation and does not support calcium-dependent facilitation of voltage-dependent P/Q-type calcium channels. Causes calcium-dependent facilitation and inhibits inactivation of L-type calcium channels by binding to the same sites as calmodulin in the C-terminal domain of CACNA1C, but resulting in an opposit effects on channel function. Suppresses the calcium-dependent inactivation of CACNA1D (By similarity). Inhibits TRPC5 channels. Prevents NMDA receptor-induced cellular degeneration (By similarity).[1] [2] [3] [4] [5] Publication Abstract from PubMedCalcium-binding protein 1 (CaBP1), a calmodulin (CaM) homolog, endows certain voltage-gated calcium channels (Ca(V)s) with unusual properties. CaBP1 inhibits Ca(V)1.2 calcium-dependent inactivation (CDI) and introduces calcium-dependent facilitation (CDF). Here, we show that the ability of CaBP1 to inhibit Ca(V)1.2 CDI and induce CDF arises from interaction between the CaBP1 N-lobe and interlobe linker residue Glu94. Unlike CaM, where functional EF hands are essential for channel modulation, CDI inhibition does not require functional CaBP1 EF hands. Furthermore, CaBP1-mediated CDF has different molecular requirements than CaM-mediated CDF. Overall, the data show that CaBP1 comprises two structural modules having separate functions: similar to CaM, the CaBP1 C-lobe serves as a high-affinity anchor that binds the Ca(V)1.2 IQ domain at a site that overlaps with the Ca(2)+/CaM C-lobe site, whereas the N-lobe/linker module houses the elements required for channel modulation. Discovery of this division provides the framework for understanding how CaBP1 regulates Ca(V)s. Structural basis for the differential effects of CaBP1 and calmodulin on Ca(V)1.2 calcium-dependent inactivation.,Findeisen F, Minor DL Jr Structure. 2010 Dec 8;18(12):1617-31. PMID:21134641[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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