Binding of the G protein βγ subunit to multiple regions of G protein‐gated inward‐rectifying K+ channels

FEBS Letters

Jan, Lily Y¹  Huang, Chou-Long¹  Jan, Yuh Nung¹ 

[1] Howard Hughes Medical Institute, Departments of Physiology and Biochemistry and Biophysics, the University of California at San Francisco, CA 94143-0724, USA

关键词: Direct protein-protein interaction;    Weaver mutation;    G-protein-gated inwardly rectifying K+ channel;    Fusion protein;    Gβγ binding;    Glutathione-S-transferase;   

DOI  :  10.1016/S0014-5793(97)00197-X

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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 GIRK 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.

【 授权许可】

Unknown