1qx7
From Proteopedia
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Crystal structure of apoCaM bound to the gating domain of small conductance Ca2+-activated potassium channel
Overview
Small conductance Ca2+-activated K+ channels (SK channels) are composed of, the pore-forming alpha subunit and calmodulin (CaM). CaM binds to a region, of the alpha subunit called the CaM binding domain (CaMBD), located, intracellular and immediately C-terminal to the inner helix gate, in, either the presence or absence of Ca2+. SK gating occurs when Ca2+ binds, the N lobe of CaM thereby transmitting the signal to the attached inner, helix gate to open. Here we present crystal structures of apoCaM and, apoCaM/SK2 CaMBD complex. Several apoCaM crystal forms with multiple (12), packing environments reveal the same EF hand domain-swapped dimer, providing potentially new insight into CaM regulation. The apoCaM/SK2, CaMBD structure, combined with our Ca2+/CaM/CaMBD structure suggests that, Ca2+ binding induces folding and dimerization of the CaMBD, which causes, large CaMBD-CaM C lobe conformational changes, including a >90 degrees, rotation of the region of the CaMBD directly connected to the gate.
About this Structure
1QX7 is a Protein complex structure of sequences from Rattus norvegicus. Full crystallographic information is available from OCA.
Reference
Crystal structures of apocalmodulin and an apocalmodulin/SK potassium channel gating domain complex., Schumacher MA, Crum M, Miller MC, Structure. 2004 May;12(5):849-60. PMID:15130477
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