title: Functional and biophysical analysis of the C-terminus of the CGRP-receptor; a family B GPCR.
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.
authors.affiliation: School of Biosciences, University of Birmingham, UK.
authors.forename: Matthew
authors.initials: M
authors.lastname: Conner
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Hicks
authors.forename: Tim
authors.initials: T
authors.lastname: Dafforn
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Knowles
authors.forename: Christian
authors.initials: C
authors.lastname: Ludwig
authors.forename: Susan
authors.initials: S
authors.lastname: Staddon
authors.forename: Michael
authors.initials: M
authors.lastname: Overduin
authors.forename: Ulrich L
authors.initials: UL
authors.lastname: Günther
authors.forename: Johannes
authors.initials: J
authors.lastname: Thome
authors.forename: Mark
authors.initials: M
authors.lastname: Wheatley
authors.forename: David R
authors.initials: DR
authors.lastname: Poyner
authors.forename: Alex C
authors.initials: AC
authors.lastname: Conner
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D015740:Calcitonin Gene-Related Peptide / Q000737:chemistry / Q000378:metabolism*; D002522:Chlorocebus aethiops; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D018015:Receptors, Calcitonin Gene-Related Peptide / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*
chemical_list: D018015:Receptors, Calcitonin Gene-Related Peptide; D015740:Calcitonin Gene-Related Peptide