Structural highlights
Function
[CALM_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. [SCN2A_RAT] Mediates the voltage-dependent sodium ion permeability of excitable membranes. Assuming opened or closed conformations in response to the voltage difference across the membrane, the protein forms a sodium-selective channel through which Na(+) ions may pass in accordance with their electrochemical gradient.
Publication Abstract from PubMed
The 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 Also
References
- ↑ Feldkamp MD, Yu L, Shea MA. Structural and Energetic Determinants of Apo Calmodulin Binding to the IQ Motif of the Na(V)1.2 Voltage-Dependent Sodium Channel. Structure. 2011 Mar 23. PMID:21439835 doi:10.1016/j.str.2011.02.009
