Functional and biophysical analysis of the C-terminus of the CGRP-receptor; a family B GPCR

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Abstract

G-protein coupled receptors (GPCRs) typically have a functionally important C-terminus which, in the largest subfamily (family A), includes a membrane-parallel eighth helix. Mutations of this region are associated with several diseases. There are few C-terminal studies on the family B GPCRs and no data supporting the existence of a similar eighth helix in this second major subfamily, which has little or no sequence homology to family A GPCRs. Here we show that the C-terminus of a family B GPCR (CLR) has a disparate region from N400 to C436 required for CGRP-mediated internalization, and a proximal region of twelve residues (from G388 to W399), in a similar position to the family A eighth helix, required for receptor localization at the cell surface. A combination of circular and linear dichroism, fluorescence and modified waterLOGSY NMR spectroscopy (SALMON) demonstrated that a peptide mimetic of this domain readily forms a membrane-parallel helix anchored to the liposome by an interfacial tryptophan residue. The study reveals two key functions held within the C-terminus of a family B GPCR and presents support for an eighth helical region with striking topological similarity to the nonhomologous family A receptor. This helix structure appears to be found in most other family B GPCRs.

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Original languageEnglish
Pages (from-to)8434-8444
Number of pages11
JournalBiochemistry
Volume47
Issue number32
DOIs
Publication statusPublished - 18 Jul 2008

    Keywords

  • G-protein coupled receptors, GPCRs, C-terminus, membrane-parallel, eighth helix, mutations, N400, C436, CGRP-mediated internalization, G388, W399), receptor localization, cell surface, dichroism, waterLOGSY, NMR spectroscopy, SALMON, peptide, interfacial tryptophan residue

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