3dvk
From Proteopedia
Crystal Structure of Ca2+/CaM-CaV2.3 IQ domain complex
Structural highlights
Function[CAC1E_RAT] Voltage-sensitive calcium channels (VSCC) mediate the entry of calcium ions into excitable cells and are also involved in a variety of calcium-dependent processes, including muscle contraction, hormone or neurotransmitter release, gene expression, cell motility, cell division and cell death. The isoform alpha-1E gives rise to R-type calcium currents. R-type calcium channels belong to the 'high-voltage activated' (HVA) group and are blocked by nickel, and partially by omega-agatoxin-IIIA (omega-Aga-IIIA). They are however insensitive to dihydropyridines (DHP), omega-conotoxin-GVIA (omega-CTx-GVIA), and omega-agatoxin-IVA (omega-Aga-IVA). Calcium channels containing alpha-1E subunit could be involved in the modulation of firing patterns of neurons which is important for information processing. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedCalcium influx drives two opposing voltage-activated calcium channel (Ca(V)) self-modulatory processes: calcium-dependent inactivation (CDI) and calcium-dependent facilitation (CDF). Specific Ca(2+)/calmodulin (Ca(2+)/CaM) lobes produce CDI and CDF through interactions with the Ca(V)alpha(1) subunit IQ domain. Curiously, Ca(2+)/CaM lobe modulation polarity appears inverted between Ca(V)1s and Ca(V)2s. Here, we present crystal structures of Ca(V)2.1, Ca(V)2.2, and Ca(V)2.3 Ca(2+)/CaM-IQ domain complexes. All display binding orientations opposite to Ca(V)1.2 with a physical reversal of the CaM lobe positions relative to the IQ alpha-helix. Titration calorimetry reveals lobe competition for a high-affinity site common to Ca(V)1 and Ca(V)2 IQ domains that is occupied by the CDI lobe in the structures. Electrophysiological experiments demonstrate that the N-terminal Ca(V)2 Ca(2+)/C-lobe anchors affect CDF. Together, the data unveil the remarkable structural plasticity at the heart of Ca(V) feedback modulation and indicate that Ca(V)1 and Ca(V)2 IQ domains bear a dedicated CDF site that exchanges Ca(2+)/CaM lobe occupants. Structures of CaV2 Ca2+/CaM-IQ domain complexes reveal binding modes that underlie calcium-dependent inactivation and facilitation.,Kim EY, Rumpf CH, Fujiwara Y, Cooley ES, Van Petegem F, Minor DL Jr Structure. 2008 Oct 8;16(10):1455-67. PMID:18940602[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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