RT Journal Article
SR Electronic
T1 The Amino Terminus of Receptor Activity Modifying Proteins Is a Critical Determinant of Glycosylation State and Ligand Binding of Calcitonin Receptor-Like Receptor
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 1054
OP 1059
DO 10.1124/mol.55.6.1054
VO 55
IS 6
A1 Neil J. Fraser
A1 Alan Wise
A1 Jason Brown
A1 Linda M. McLatchie
A1 Martin J. Main
A1 Steven M. Foord
YR 1999
UL http://molpharm.aspetjournals.org/content/55/6/1054.abstract
AB The calcitonin receptor-like receptor (CRLR) can function as either a receptor for calcitonin gene-related peptide (CGRP) or for adrenomedullin (ADM), depending upon the coexpression of a novel family of single transmembrane proteins, which we have called receptor activity modifying proteins or RAMPs. RAMPs 1, 2, and 3 transport CRLR to the plasma membrane with similar efficiencies, however RAMP1 presents CRLR as a terminally glycosylated, mature glycoprotein and a CGRP receptor, whereas RAMPs 2 and 3 present CRLR as an immature, core glycosylated ADM receptor. Characterization of the RAMP2/CRLR and RAMP3/CRLR receptors in HEK293T cells by radioligand binding (125I-ADM as radioligand), functional assay (cAMP measurement), or biochemical analysis (SDS-polyacrylamide gel electrophoresis) revealed them to be indistinguishable, even though RAMPs 2 and 3 share only 30% identity. Chimeric proteins were created with the transmembrane and cytosolic portions of RAMP1 associated with the amino terminus of RAMP2 (RAMP2/1) and vice versa (RAMP1/2). Coexpression of RAMP2/1 with CRLR formed a core glycosylated ADM receptor, whereas the RAMP1/2 chimera generated both core glycosylated and mature forms of CRLR and enabled both ADM and CGRP receptor binding. Hence, the glycosylation state of CRLR appears to correlate with its pharmacology.