The extracellular domain of receptor activity-modifying protein 1 is sufficient for calcitonin receptor-like receptor function.
A functional calcitonin gene-related peptide (CGRP) receptor requires dimerization of calcitonin receptor-like receptor (CRLR) with receptor activity-modifying protein 1 (RAMP 1). To determine the function of the three domains (extracellular, ECD; transmembrane, TM; and tail domains) of human RAMP 1, three mutants were constructed: RAMP 1 without the cytoplasmic tail, a chimera consisting of the ECD of RAMP 1 and the TM and tail of the platelet-derived growth factor receptor, and the ECD of RAMP 1 alone. These RAMP 1 mutants were examined for their ability to associate with CRLR to effect CGRP-stimulated cAMP accumulation, CGRP binding, CRLR trafficking, and cell surface expression. All RAMP 1 mutants were able to associate with CRLR with full efficacy for CGRP-stimulated cAMP accumulation. However, the RAMP 1/platelet-derived growth factor receptor chimera demonstrated a 10-fold decrease in potency for CGRP signaling and binding, and the RAMP 1-ECD mutant had a 4000-fold decrease in potency. In conclusion, the ECD of RAMP 1 is sufficient for normal CRLR association and efficacy. The presence of a TM domain and the specific sequence of the RAMP 1 TM domain contribute to CGRP affinity and potency. The C-terminal tail of RAMP 1 is unnecessary for CRLR function.
Fitzsimmons
Timothy J
TJ
Digestive Diseases Branch, National Institute Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-1804, USA.
Zhao
Xilin
X
Wank
Stephen A
SA
D000595:Amino Acid Sequence; D001921:Brain / Q000378:metabolism; D058286:Calcitonin Receptor-Like Protein; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D049452:Green Fluorescent Proteins; D006801:Humans; D015151:Immunoblotting; D047908:Intracellular Signaling Peptides and Proteins; D008164:Luminescent Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D058261:Receptor Activity-Modifying Proteins; D018003:Receptors, Calcitonin / Q000737:chemistry* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection
C545578:CALCRL protein, human; D058286:Calcitonin Receptor-Like Protein; D047908:Intracellular Signaling Peptides and Proteins; D008164:Luminescent Proteins; D008565:Membrane Proteins; D058261:Receptor Activity-Modifying Proteins; D018003:Receptors, Calcitonin; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D000242:Cyclic AMP