Primary sequence and immunological characterization of beta-subunit of high conductance Ca(2+)-activated K+ channel from smooth muscle.
Year: 1994
Type: article
Abstract: The charybdotoxin receptor, purified from bovine tracheal smooth muscle, consists of two subunits (alpha and beta) and, when reconstituted into planar lipid bilayers, forms functional high conductance Ca(2+)-activated K+ channels. Amino acid sequence, obtained from proteolytic fragments of the beta-subunit, was used to design oligonucleotide probes with which cDNAs encoding this protein were isolated. The cDNAs encode a protein of 191 amino acids that contains two hydrophobic (putative transmembrane) domains and bears little sequence homology to subunits of other known ion channels. Site-directed antisera, raised against putative extracellular epitopes of this protein, specifically immunoprecipitated 125I-labeled Bolton-Hunter beta-subunit as well as [125I]charybdotoxin-cross-linked beta-subunit. Under nondenaturing conditions, however, these anti-beta sera immunoprecipitated a complex consisting of both the alpha- and beta-subunits. The data demonstrate that, in vivo, the high conductance Ca(2+)-activated K+ channel exists as a multimer containing both alpha- and beta-subunits, and this cDNA represents the first beta-subunit of a potassium channel cloned to date. Furthermore, we demonstrate that the cloned protein is the subunit to which charybdotoxin is specifically and covalently incorporated when cross-linked to the channel.
Source: Journal of Biological Chemistry
Institution: Merck & Co., Inc., Rahway, NJ, USA (United States)
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,430
OpenAlex ID: W1602374960