Figure 7.

Working Model for the Roles of EMC and Sec61 Complex in GPCR Biogenesis

The left half of the diagram shows the normal situation (wild-type), and the right half depicts the consequence of EMC deletion (ΔEMC). After targeting via SRP, the N_exo signal anchor is inserted via EMC, likely near the Sec61 complex to which the ribosome is probably docked. Downstream TMDs are inserted by Sec61. In the absence of EMC, the N_exo signal anchor of most of the nascent chains fails to insert in the correct topology, resulting in a misfolded and degraded protein. Depending on the substrate, some nascent chains are inserted appropriately by the Sec61 complex even in the absence of EMC, leading to a small population of correctly folded final protein.