Design, synthesis and functional characterization of a pentameric channel protein that mimics the presumed pore structure of the nicotinic cholinergic receptor

FEBS Letters

Montal, Mauricio²  Montal, Myrta Oblatt²  Tomich, John M.¹  Iwamoto, Takeo¹ 

[1] Department of Biochemistry and Biotechnology Core Facility, Kansas State University, Manhattan, KS 66506-3702, USA;Department of Biology, University of California San Diego, La Jolla, CA 92093-0319, USA

关键词: Neurotransmitter receptor;    Ionic channel;    Protein design;    Lipid bilayer;    Signal transduction;    AChR;    acetylcholine receptor;    γ;    single channel conductance;    POPE;    1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine;    POPC;    1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine;    τc;    closed times;    τo;    open times;   

DOI  :  10.1016/0014-5793(93)80599-P

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Nicotinic cholinergic receptors are membrane proteins composed of five subunits organized around a central aqueous pore. A pentameric channel protein, T₅M2δ, that emulates the presumed pore-forming structure of this receptor was generated by assembling five helix-forming peptide modules at the lysine ϵ-amino groups of the 11-residue template [K^∗AK^∗KK^∗PGK^∗EK^∗G], where ^∗ indicates attachment sites. Helical modules represent the sequence of the M2 segment of the Torpedo californica acetylcholine receptor (AChR) δ subunit; M2 segments are considered involved in pore-lining. Purified T₅M2δ migrates in SDS-PAGE with an apparent M _r~14,000, concordant with a protein of 126 residues. T₅M2δ forms cation-selective channels when reconstituted in planar lipid bilayers. The single channel conductance in symmetric 0.5 M K.C1 is 40 pS. This value approximates the 45 pS single channel conductance characteristic of authentic purified Torpedo AChR, recorded under otherwise identical conditions. These results, together with conformational energy calculations, support the notion that a bundle of five amphipathic a-helices is a plausible structural motif underlying the inner bundle that forms the pore of the pentameric AChR channel.

【 授权许可】

Unknown