RAMP3, also known as receptor activity modifying protein 3, is a member of the RAMP family of single-transmembrane-domain proteins, called receptor (calcitonin) activity modifying proteins (RAMPs). It is required to transport calcitonin-receptor-like receptor (CRLR) to the plasma membrane. CRLR can function as either a calcitonin gene-related peptide (CGRP) receptor or an adrenomedullin receptor, depending on which members of the RAMP family are expressed. In the presence of this (RAMP3) protein, CRLR functions as an adrenomedullin receptor. Recombinant human RAMP3 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.