Calcitonin receptor-like receptor (CLR) influences posttranslational events of receptor activity-modifying proteins (RAMPs)

Abstract

Adrenomedullins (AM) form a multifunctional subfamily of the calcitonin gene-related peptide (CGRP) superfamily, the members of which exert their physiological roles through a 1:1 combination of calcitonin receptor-like receptors (CLRs) and receptor activity-modifying proteins (RAMPs). It has been shown that RAMPs can modify the biochemical properties of CLRs; for example, RAMP escorts CLR to the plasma membrane, affects glycosylation state of CLR, and transforms the ligand selectivity of CLR, but on the other hand the effects of CLRs on the biochemical and functional properties of the partner RAMPs are not well established. In this study, using pufferfish (mefugu, mf) homolog, we revealed that mfCLR1 could affect the post-translational modification and trafficking pathway of mfRAMP1. In addition, mfCLRs boosted mfRAMP1, mfRAMP2b, and mfRAMP3 translocation to cell surface. We further revealed that mfRAMPs, except mfRAMP1 and mfRAMP3, could be expressed as multimers on the plasma membrane. However, only monomeric form of mfRAMP2a, mfRAMP4, and mfRAMP5 could heteromerize with mfCLR1 but not with mfCLR2 or mfCLR3, which was consistent with their abilities to induce cAMP response. Collectively our results indicate that the glycosylation, subcellular trafficking, and pharmacological properties of the components of RAMP–CLR receptor complexes are regulated in an interdependent manner.