1jo6

Solution structure of the cytoplasmic N-terminus of the BK beta-subunit KCNMB2Solution structure of the cytoplasmic N-terminus of the BK beta-subunit KCNMB2

Structural highlights 1jo6 is a 1 chain structure with sequence from Homo sapiens. Full experimental information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Solution NMR Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function KCMB2_HUMAN Regulatory subunit of the calcium activated potassium KCNMA1 (maxiK) channel. Modulates the calcium sensitivity and gating kinetics of KCNMA1, thereby contributing to KCNMA1 channel diversity. Acts as a negative regulator that confers rapid and complete inactivation of KCNMA1 channel complex. May participate in KCNMA1 inactivation in chromaffin cells of the adrenal gland or in hippocampal CA1 neurons. Publication Abstract from PubMed The auxiliary beta-subunit KCNMB2 (beta(2)) endows the non-inactivating large conductance Ca(2+)- and voltage-dependent potassium (BK) channel with fast inactivation. This process is mediated by the N terminus of KCNMB2 and closely resembles the "ball-and-chain"-type inactivation observed in voltage-gated potassium channels. Here we investigated the solution structure and function of the KCNMB2 N terminus (amino acids 1-45, BKbeta(2)N) using NMR spectroscopy and patch clamp recordings. BKbeta(2)N completely inactivated BK channels when applied to the cytoplasmic side; its interaction with the BK alpha-subunit is characterized by a particularly slow dissociation rate and an affinity in the upper nanomolar range. The BKbeta(2)N structure comprises two domains connected by a flexible linker: the pore-blocking "ball domain" (formed by residues 1-17) and the "chain domain" (between residues 20-45) linking it to the membrane segment of KCNMB2. The ball domain is made up of a flexible N terminus anchored at a well ordered loop-helix motif. The chain domain consists of a 4-turn helix with an unfolded linker at its C terminus. These structural properties explain the functional characteristics of BKbeta(2)N-mediated inactivation. NMR structure of the "ball-and-chain" domain of KCNMB2, the beta 2-subunit of large conductance Ca2+- and voltage-activated potassium channels.,Bentrop D, Beyermann M, Wissmann R, Fakler B J Biol Chem. 2001 Nov 9;276(45):42116-21. Epub 2001 Aug 21. PMID:11517232 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Potassium channel 3D structures

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