The eukaryotic signal recognition particle (SRP) receptor is a heterodimeric complex comprising a soluble alpha subunit and a beta subunit that is an integral membrane protein of the endoplasmic reticulum. Nascent SRP-bound polypeptides interact with the SRP receptor and are then transferred to the Sec61 translocon, which either integrates the protein into the lipid bilayer or translocates it across the membrane to enter the secretory pathway. (Adapted from PMID:23414305.)