Abstract
Inward rectifier K+ (Kir) channels are activated by phosphatidylinositol-(4,5)-bisphosphate (PIP2), but G protein-gated Kir (KG) channels further require either G protein βγ subunits (Gβγ) or intracellular Na+ for their activation. To reveal the mechanism(s) underlying this regulation, we compared the crystal structures of the cytoplasmic domain of KG channel subunit Kir3.2 obtained in the presence and the absence of Na+. The Na+-free Kir3.2, but not the Na+-plus Kir3.2, possessed an ionic bond connecting the N terminus and the CD loop of the C terminus. Functional analyses revealed that the ionic bond between His-69 on the N terminus and Asp-228 on the CD loop, which are known to be critically involved in Gβγ- and Na+-dependent activation, lowered PIP2 sensitivity. The conservation of these residues within the KG channel family indicates that the ionic bond is a character that maintains the channels in a closed state by controlling the PIP2 sensitivity.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
