Receptor activity-modifying protein

Receptor activity-modifying proteins (RAMPs) are a class of protein which interact with and modulate the activities of several Class B G Protein-Coupled Receptors including the receptors for secretin, calcitonin (CT), glucagon, and vasoactive intestinal peptide (VIP). There are three distinct types of RAMPs, designated RAMP1, RAMP2, and RAMP3, each encoded by a separate gene.

Function
Currently the function of RAMPs is divided into classes activities. When associated with the Calcitonin receptor (CTR) or Calcitonin receptor-like (CALCRL) (below) 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 (KO) have grossly abnormal phenotypes. The likelihood is that the phenotype of RAMP2 KO mice is more connected with the abolition of most adrenomedullin (AM) signalling than effects on trafficking of other receptors as those mice are almost identical to AM KO mice.

Types
Association of RAMPs with either the CT or CALCRL proteins form 6 different receptors from the calcitonin receptor family: