Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604105
Title: Regulation of G protein-gated K+channels
Author: Ho, H. M. I.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 1999
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Abstract:
The aims of my project were (i) to elucidate the molecular mechanism of Na+-dependent activation of GIRK channel, and (ii) to investigate the effect of intracellular acidification on GIRK channel activity. Intracellular Na+ dose-dependently activated the wild type GIRK2 homomeric and GIRK1/GIRK2 heteromeric channels. The proximal C-terminal region of the GIRK2 subunit was shown to mediate the Na+-dependent activation of both homomeric and heteromeric channels. Within this region, GIRK2 has an aspartate at position 226, whereas GIRK1 has an asparagine at the equivalent position (217). A single point mutation, D226N, in GIRK2, abolished the Na+-dependent activation of both the homomeric and heteromeric channels without affecting their ability to be activated via the m2-muscarinic receptors. Neutralizing a nearby charge, E234S had no effect. A reverse mutation in the GIRK1 subunit, N217D, was sufficient to restore the Na+-dependent activation of the GIRK1N217D/GIRK2D226N heteromeric channels. Thus, the aspartate 226 in GIRK2 plays a crucial role in Na+-dependent activation of both the GIRK2 homomeric and GIRK1/GIRK2 heteromeric channels. Interestingly, intracellular Na+ slowed the time-course of inhibition by PIP2-specific antibody to a similar extent as the neutralization of the aspartate 226 in GIRK2 did. This suggests that intracellular Na2+ binds to the GIRK2 subunit to neutralize the aspartate 226 and to promote the binding of PIP2 to a nearby region of the C-terminus. This activates the GIRK2 homomeric and GIRK1/GIRK2 heteromeric channels.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.604105  DOI: Not available
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