1QX7

Crystal structure of apoCaM bound to the gating domain of small conductance Ca2+-activated potassium channel

Summary for 1QX7

• Entry DOI: 10.2210/pdb1qx7/pdb
• Related: 1G4Y 1QX5
• Descriptor: Calmodulin, Small conductance calcium-activated potassium channel protein 2 (2 entities in total)
• Functional Keywords: apocalmodulin, sk channel, small conductance ca2+ activated k+ channel, cambd, gating domain, ca2+-activated gating, functioanl bipartism, signaling protein
• Biological source: Rattus norvegicus (Norway rat); More
• Cellular location: Cytoplasm, cytoskeleton, spindle: P62161; Membrane; Multi-pass membrane protein: P70604
• Total number of polymer chains: 6
• Total formula weight: 95934.02

Authors

Schumacher, M.A.,Crum, M.,Miller, M.C. (deposition date: 2003-09-04, release date: 2004-08-31, Last modification date: 2024-10-30)

Primary citation

Schumacher, M.A.,Crum, M.,Miller, M.C.
Crystal structures of apocalmodulin and an apocalmodulin/SK potassium channel gating domain complex.
STRUCTURE, 12:849-860, 2004

PubMed Abstract: 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.

PubMed: 15130477
DOI: 10.1016/j.str.2004.03.017

Experimental method

X-RAY DIFFRACTION (3.09 Å)