1JO6

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

Summary for 1JO6

• Entry DOI: 10.2210/pdb1jo6/pdb
• NMR Information: BMRB: 5092
• Descriptor: potassium large conductance calcium-activated channel, subfamily M, beta member 2 (1 entity in total)
• Functional Keywords: helix, ion channel, cytoplasmic part of, metal transport, membrane protein
• Cellular location: Membrane; Multi-pass membrane protein: Q9Y691
• Total number of polymer chains: 1
• Total formula weight: 5380.06

Authors

Bentrop, D.,Beyermann, M.,Wissmann, R.,Fakler, B. (deposition date: 2001-07-27, release date: 2001-11-16, Last modification date: 2024-05-22)

Primary citation

Bentrop, D.,Beyermann, M.,Wissmann, R.,Fakler, B.
NMR structure of the "ball-and-chain" domain of KCNMB2, the beta 2-subunit of large conductance Ca2+- and voltage-activated potassium channels.
J.Biol.Chem., 276:42116-42121, 2001

PubMed Abstract: 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.

PubMed: 11517232
DOI: 10.1074/jbc.M107118200

Experimental method

SOLUTION NMR