1kkd

Publication Abstract from PubMed

Small conductance Ca(2+)-activated potassium (SK) channels underlie the afterhyperpolarization that follows the action potential in many types of central neurons. SK channels are voltage-independent and gated solely by intracellular Ca(2+) in the submicromolar range. This high affinity for Ca(2+) results from Ca(2+)-independent association of the SK alpha-subunit with calmodulin (CaM), a property unique among the large family of potassium channels. Here we report the solution structure of the calmodulin binding domain (CaMBD, residues 396-487 in rat SK2) of SK channels using NMR spectroscopy. The CaMBD exhibits a helical region between residues 423-437, whereas the rest of the molecule lacks stable overall folding. Disruption of the helical domain abolishes constitutive association of CaMBD with Ca(2+)-free CaM, and results in SK channels that are no longer gated by Ca(2+). The results show that the Ca(2+)-independent CaM-CaMBD interaction, which is crucial for channel function, is at least in part determined by a region different in sequence and structure from other CaM-interacting proteins.

A helical region in the C terminus of small-conductance Ca2+-activated K+ channels controls assembly with apo-calmodulin.,Wissmann R, Bildl W, Neumann H, Rivard AF, Klocker N, Weitz D, Schulte U, Adelman JP, Bentrop D, Fakler B J Biol Chem. 2002 Feb 8;277(6):4558-64. Epub 2001 Nov 26. PMID:11723128^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.