G beta gamma directly binds to the carboxyl terminus of the G protein-gated muscarinic K+ channel, GIRK1.
beta gamma Subunits of heterotrimeric GTP-binding proteins (G beta gamma) activate the inwardly rectifying muscarinic K+ channel, GIRK1. The significant role for the carboxyl (C) terminus of GIRK1 in this interaction has been suggested. However, it is still unknown whether G beta gamma directly interacts with GIRK1. To elucidate the molecular basis of G beta gamma-activation of GIRK1, we examined the binding properties of G beta gamma to the C terminus of GIRK1 cloned from mouse brain cDNA library (MB-GIRK1). The C terminus of MB-GIRK1 fused with glutathione S-transferase directly bound to purified G beta gamma. Incubation of the C terminus with Gi pretreated with GTP gamma S, but not with GDP, resulted in the binding of Gi beta gamma to the protein. Purified G alpha-GDP, but not G alpha-GTP gamma S, inhibited the binding of G beta gamma to the fusion protein. These results indicate that G beta gamma dissociated from G alpha may directly bind to the C terminus of GIRK1.
Inanobe
A
A
Department of Cell Biology and Signaling, Yamagata University School of Medicine, Japan.
Morishige
K I
KI
Takahashi
N
N
Ito
H
H
Yamada
M
M
Takumi
T
T
Nishina
H
H
Takahashi
K
K
Kanaho
Y
Y
Katada
T
T
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D001921:Brain / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D066298:In Vitro Techniques; D015640:Ion Channel Gating; D051379:Mice; D008969:Molecular Sequence Data; D015221:Potassium Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D024661:Potassium Channels, Inwardly Rectifying; D011487:Protein Conformation; D051381:Rats; D011976:Receptors, Muscarinic / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D018076:DNA, Complementary; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D011976:Receptors, Muscarinic; D011993:Recombinant Fusion Proteins; D019204:GTP-Binding Proteins