Abstract
We have previously shown that direct binding of the βγ subunit of G protein (Gβγ) to both the N-terminal domain and the C-terminal domain of a cloned G protein-gated inward rectifying K+ channel subunit, GIRK1, is important for channel activation. We have now further localized the Gβγ binding region in the N-terminal domain of GIRK1 to amino acids 34-86 and the Gβγ binding region in the C-terminal domain of GIRK1 to two separate fragments of amino acids 318-374 and amino acids 390-462. Of the four cloned mammalian GIRK subunits, GIRK1-4, GIRK1 and 4 form heteromeric K+ channels in the heart and similar channels in the brain include heteromultimers of GIRK1 and 2, and possibly other GLRK homomultimers and heteromultimers. We found that the N-terminal and the C-terminal domains of all four GIRKs bound Gβγ. The Gβγ binding activities for the C-terminal domains of GIRK2-4 were lower than that for the C-terminal domain of GIRK1. The higher Gβγ binding activity for the C-terminal domain of GIRK1 is due to amino acids 390-462 which are unique to GIRK1. We also found that the N-terminal and C-terminal domains of GIRKs interacted with each other, and the N-terminal domain of either GIRK1 or GIRK4 together with the C-terminal domain of GIRK1 exhibited much enhanced binding of Gβγ. These results are consistent with the idea that the N- and C-terminal domains of the cardiac G protein-gated K+ channel subunits may interact with each other to form higher affinity binding site(s) for Gβγ.
Original language | English (US) |
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Pages (from-to) | 291-298 |
Number of pages | 8 |
Journal | FEBS Letters |
Volume | 405 |
Issue number | 3 |
DOIs | |
State | Published - Apr 1 1997 |
Keywords
- Direct protein-protein interaction
- Fusion protein
- G-protein-gated inwardly rectifying K channel
- Glutathione-S-transferase
- Gβγ binding
- Weaver mutation
ASJC Scopus subject areas
- Biophysics
- Structural Biology
- Biochemistry
- Molecular Biology
- Genetics
- Cell Biology