Yeast screen for constitutively active mutant G protein-activated potassium channels.
GIRK2 is a major contributor to G protein-activated inward rectifier potassium channels in the mammalian brain. How GIRK channels open upon contact with Gbetagamma remains unknown. Using a yeast genetic screen to select constitutively active mutants from a randomly mutagenized GIRK2 library, we identified five gating mutations at four residues in the transmembrane domain. Further mutagenesis indicates that GIRK channel opening involves a rotation of the transmembrane segments, bringing one of these residues (V188) to a pore-lining position in the open conformation. Combined with double-mutant studies, these findings suggest that GIRK channels gate by moving from the open conformation inferred from our yeast study of Kir2.1 to a closed conformation perhaps resembling the known KcsA structure.
Yi
B A
BA
Departments of Physiology and Biochemistry, Howard Hughes Medical Institute, University of California, San Francisco, 533 Parnassus Avenue, San Francisco, CA 94143, USA.
Lin
Y F
YF
Jan
Y N
YN
Jan
L Y
LY
D000595:Amino Acid Sequence; D000818:Animals; D004252:DNA Mutational Analysis; D004553:Electric Conductivity; D005260:Female; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D015870:Gene Expression; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism*; D015640:Ion Channel Gating / Q000235:genetics; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009865:Oocytes / Q000378:metabolism; D015221:Potassium Channels / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D024661:Potassium Channels, Inwardly Rectifying; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D016415:Sequence Alignment; D013329:Structure-Activity Relationship; D014981:Xenopus
D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; C118981:G-protein Beta gamma; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D020962:Heterotrimeric GTP-Binding Proteins