4hex | pdb_00004hex
A novel conformation of calmodulin
Structural highlights
FunctionCALM1_MOUSE Calmodulin mediates the control of a large number of enzymes, ion channels, aquaporins and other proteins through calcium-binding. Among the enzymes to be stimulated by the calmodulin-calcium complex are a number of protein kinases and phosphatases. Together with CCP110 and centrin, is involved in a genetic pathway that regulates the centrosome cycle and progression through cytokinesis. Is a regulator of voltage-dependent L-type calcium channels. Mediates calcium-dependent inactivation of CACNA1C. Positively regulates calcium-activated potassium channel activity of KCNN2. Forms a potassium channel complex with KCNQ1 and regulates electrophysiological activity of the channel via calcium-binding. Acts as a sensor to modulate the endoplasmic reticulum contacts with other organelles mediated by VMP1:ATP2A2 (By similarity).[UniProtKB:P0DP23] Publication Abstract from PubMedCalmodulin (CaM) is a highly conserved eukaryotic protein that binds specifically to more than 100 target proteins in response to calcium (Ca(2+)) signal. CaM adopts a considerable degree of structural plasticity to accomplish this physiological role; however, the nature and extent of this plasticity remain to be fully understood. Here, we report the crystal structure of a novel trans conformation of ligand-free CaM where the relative disposition of two lobes of CaM is different, a conformation to-date not reported. While no major structural changes were observed in the independent N- and C-lobes as compared with previously reported structures of Ca(2+)/CaM, the central helix was tilted by approximately 90 degrees at Arg75. This is the first crystal structure of CaM to show a drastic conformational change in the central helix, and reveals one of several possible conformations of CaM to engage with its binding partner. A novel trans conformation of ligand-free calmodulin.,Kumar V, Chichili VP, Tang X, Sivaraman J PLoS One. 2013;8(1):e54834. doi: 10.1371/journal.pone.0054834. Epub 2013 Jan 29. PMID:23382982[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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