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.
Mesh Terms:
Amino Acid Sequence, Brain, Cell Line, Cell Membrane, Cyclic AMP, Dimerization, Dose-Response Relationship, Drug, Flow Cytometry, Green Fluorescent Proteins, Humans, Immunoblotting, Intracellular Signaling Peptides and Proteins, Luminescent Proteins, Membrane Proteins, Molecular Sequence Data, Mutation, Precipitin Tests, Protein Binding, Protein Structure, Tertiary, Receptors, Calcitonin, Recombinant Fusion Proteins, Signal Transduction, Transfection
J. Biol. Chem.
Date: Apr. 18, 2003
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