Required for the post-translational delivery of tail-anchored (TA) proteins to the endoplasmic reticulum. Together with CAMLG/GET2, acts as a membrane receptor for soluble GET3/TRC40, which recognizes and selectively binds the transmembrane domain of TA proteins in the cytosol. Required to ensure correct topology and ER insertion of CAMLG. Component of the Golgi to ER traffic (GET) complex, which is composed of GET1/WRB, CAMLG/GET2 and GET3. Within the complex, GET1 and CAMLG form a heterotetramer which is stabilized by phosphatidylinositol binding and which binds to the GET3 homodimer. Interacts with CAMLG (via C-terminus). GET3 shows a higher affinity for CAMLG than for GET1. Belongs to the WRB/GET1 family.