Receptor activity-modifying protein


Receptor activity-modifying proteins are a class of protein that interact with and modulate the activities of several Class B G protein-coupled receptors including the receptors for secretin, calcitonin, glucagon, and vasoactive intestinal peptide. There are three distinct types of RAMPs in mammals, designated RAMP1, RAMP2, and RAMP3, each encoded by a separate gene.

Function

Currently, the function of RAMPs is divided into classes of activities. When associated with the Calcitonin receptor or Calcitonin receptor-like , RAMPs can change the selectivity of the receptor for a specific hormone. In the cases of the other receptors mentioned, however, there is no evidence that they can do this, but instead function to regulate trafficking of receptors from the ER / golgi to the membrane. These functions appear to be ones where there is redundancy, as neither RAMP1 nor RAMP3 knockout mice have grossly abnormal phenotypes. The likelihood is that the phenotype of RAMP2 KO mice is more connected with the abolition of most adrenomedullin signalling than effects on trafficking of other receptors, as those mice are almost identical to AM KO mice and mice lacking the Calcitonin-like receptor which are unable to form either AM1 or AM-2 adrenomedullin receptors.

Types

Association of RAMPs with either the CT or CALCRL proteins forms 6 different receptors from the calcitonin receptor family:
GPCRRAMP isoformresultant receptor
Calcitonin receptor-likeRAMP1CGRP receptor
Calcitonin receptor-likeRAMP2adrenomedullin receptor, designated AM1
Calcitonin receptor-likeRAMP3dual CGRP/AM receptor, designated AM2
Calcitonin receptorRAMP1amylin receptor AMY1
Calcitonin receptorRAMP2amylin receptor AMY2
Calcitonin receptorRAMP3amylin receptor AMY3