RECEPTOR-ASSOCIATED PROTEIN - A SPECIALIZED CHAPERONE AND ANTAGONIST FOR MEMBERS OF THE LDL RECEPTOR GENE FAMILY

Members of the LDL receptor gene family mediate cellular uptake of var ious extracellular ligands, including lipoprotein particles. Ligand in teractions with these receptors can be antagonized by a 39 kDa recepto r-associated protein. Recent biochemical, cellular, and genetic studie s have shown that receptor-associated protein is a molecular chaperone /escort protein for LDL receptor-related protein, a member of the LDL receptor gene family that binds multiple ligands. These studies indica te that receptor-associated protein interacts with LDL receptor-relate d protein at multiple sites and assists the proper folding and disulfi de bond formation of LDL receptor-related protein within the endoplasm ic reticulum. Following the completion of folding, receptor-associated protein remains associated with the receptor during its subsequent tr afficking along the early secretory pathway, thereby preventing premat ure ligand interaction with the receptor. The ability of receptor-asso ciated protein to universally inhibit ligand interactions with members of the LDL receptor gene family underscores the use of this protein a s a tool in the study of ligand-receptor interactions. (C) 1998 Rapid Science Ltd.