Inhibition of function in Xenopus oocytes of the inwardly rectifying G-protein-activated atrial K channel (GIRK1) by overexpression of a membrane-attached form of the C-terminal tail.
Coexpression in Xenopus oocytes of the inwardly rectifying guanine nucleotide binding (G)-protein-gated K channel GIRK1 with a myristoylated modification of the (putative) cytosolic C-terminal tail [GIRK1 aa 183-501 fused in-frame to aa 1-15 of p60src and denoted src+ (183-501)] leads to a high degree of inhibition of the inward G-protein-gated K+ current. The nonmyristoylated segment, src- (183-501), is not active. Although some interference with assembly is not precluded, the evidence indicates that the main mechanism of inhibition is interference with functional activation of the channel by G proteins. In part, the tail functions as a blocking particle similar to a "Shaker ball"; it may also function by competing for the available supply of free G beta gamma liberated by hormone activation of a seven-helix receptor. The non-G-protein-gated weak inward rectifier ROMK1 is less effectively inhibited, and a Shaker K channel was not inhibited. Immunological assays show the presence of a high concentration of src+ (183-501) in the plasma membrane and the absence of any membrane forms for the nonmyristoylated segment.
Dascal
N
N
Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Ramat Aviv, Israel.
Doupnik
C A
CA
Ivanina
T
T
Bausch
S
S
Wang
W
W
Lin
C
C
Garvey
J
J
Chavkin
C
C
Lester
H A
HA
Davidson
N
N
D000595:Amino Acid Sequence; D000818:Animals; D016275:Atrial Function; D002451:Cell Compartmentation; D002458:Cell Fractionation; D004553:Electric Conductivity; D004594:Electrophysiology; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; D019204:GTP-Binding Proteins / Q000378:metabolism*; D007150:Immunohistochemistry; D015640:Ion Channel Gating; D008074:Lipoproteins / Q000302:isolation & purification / Q000494:pharmacology*; D008969:Molecular Sequence Data; D019814:Myristic Acid; D009227:Myristic Acids / Q000378:metabolism; D009865:Oocytes; D010446:Peptide Fragments / Q000302:isolation & purification / Q000494:pharmacology*; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000235:genetics; D024661:Potassium Channels, Inwardly Rectifying; D011499:Protein Processing, Post-Translational; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000235:genetics / Q000302:isolation & purification / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification / Q000494:pharmacology; D014981:Xenopus
D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; D008074:Lipoproteins; D009227:Myristic Acids; D010446:Peptide Fragments; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D011993:Recombinant Fusion Proteins; D019814:Myristic Acid; D016392:Proto-Oncogene Proteins pp60(c-src); D019204:GTP-Binding Proteins