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Modulation of reconstituted ATP‐sensitive K + channels by GTP‐binding proteins in a mammalian cell line
Author(s) -
Sánchez Jorge A.,
Gonoi Tohru,
Inagaki Nobuya,
Katada Toshiaki,
Seino Susumu
Publication year - 1998
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.1998.315bt.x
Subject(s) - kir6.2 , gtp' , g protein , sulfonylurea receptor , inward rectifier potassium ion channel , atp sensitive potassium channel , potassium channel , activator (genetics) , chemistry , biophysics , gtp binding protein regulators , gene isoform , protein kinase a , protein subunit , biochemistry , microbiology and biotechnology , receptor , biology , kinase , ion channel , enzyme , endocrinology , glibenclamide , gene , diabetes mellitus
1 The action of GTP‐binding proteins on ATP‐sensitive potassium (K ATP ) channels was investigated. K ATP channels were expressed in a mammalian cell line (COS‐1 cells) by cotransfecting vectors carrying the sulphonylurea receptor (SUR1) and BIR (Kir6.2), a member of the inward rectifier K + channel family. G proteins were also tested on K ATP channels composed of an isoform of SUR1, SUR2A, in combination with Kir6.2. 2 The α and βγ subunits of the GTP binding protein G i were tested separately in inside‐out patches under continuous recording. G α‐i1 increases the activity of SUR1‐Kir6.2 and SUR2A‐Kir6.2 channels by 200 and by 30 %, respectively. 3 G α‐i2 does not increase the activity of SUR1‐Kir6.2 channels, but increases the activity of SUR2A‐Kir6.2 channels by 30 %. 4 Control experiments showed that GTPγS, a specific activator of G proteins, and heat‐ inactivated G α‐i1 do not increase the single channel activity. 5 No effects of the other subunits (βγ) from either G i1 or G i2 on the single channel activity were observed. 5 The protein kinase C inhibitors H7 and an inhibitory peptide (FARKGALRQKNV) had no effect on the modulatory action of G α‐i1 on SUR1‐Kir6.2 channels. 6 We conclude that both types of reconstituted K ATP channels are modulated by G proteins.