2kxw
From Proteopedia
Structure of the C-domain Fragment of apo Calmodulin Bound to the IQ motif of Nav1.2
Structural highlights
FunctionCALM_PARTE Calmodulin mediates the control of a large number of enzymes, ion channels and other proteins by Ca(2+). Among the enzymes to be stimulated by the calmodulin-Ca(2+) complex are a number of protein kinases and phosphatases. Publication Abstract from PubMedThe neuronal voltage-dependent sodium channel (Na(v)1.2), essential for generation and propagation of action potentials, is regulated by calmodulin (CaM) binding to the IQ motif in its alpha subunit. A peptide (Na(v)1.2(IQp), KRKQEEVSAIVIQRAYRRYLLKQKVKK) representing the IQ motif had higher affinity for apo CaM than (Ca(2+))(4)-CaM. Association was mediated solely by the C-domain of CaM. A solution structure (2KXW.pdb) of apo (13)C,(15)N-CaM C-domain bound to Na(v)1.2(IQp) was determined with NMR. The region of Na(v)1.2(IQp) bound to CaM was helical; R1902, an Na(v)1.2 residue implicated in familial autism, did not contact CaM. The apo C-domain of CaM in this complex shares features of the same domain bound to myosin V IQ motifs (2IX7) and bound to an SK channel peptide (1G4Y) that does not contain an IQ motif. Thermodynamic and structural studies of CaM-Na(v)1.2(IQp) interactions show that apo and (Ca(2+))(4)-CaM adopt distinct conformations that both permit tight association with Na(v)1.2(IQp) during gating. Structural and Energetic Determinants of Apo Calmodulin Binding to the IQ Motif of the Na(V)1.2 Voltage-Dependent Sodium Channel.,Feldkamp MD, Yu L, Shea MA Structure. 2011 Mar 23. PMID:21439835[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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