Tail-anchored protein biosynthesis at the endoplasmic reticulum: the same but different.

The post-translational integration of tail-anchored proteins at the endoplasmic reticulum represents a novel and distinct pathway for membrane protein synthesis. Studies of various precursors, exemplified by the synaptobrevins and cytochrome b5, indicate that multiple routes may facilitate their biosynthesis. There is clear evidence that both cytosolic factors and membrane components facilitate the efficient membrane insertion of at least some tail-anchored proteins. However, the nature of these mediators is currently unknown and their identification will be an essential step in defining the molecular basis of tail-anchored protein biogenesis.