Membrane protein biosynthesis - all sewn up?

The biosynthesis of integral membrane proteins requires regions of nascent polypeptide to be inserted into, and assembled within, a lipid bilayer. Membrane protein integration at the endoplasmic reticulum (ER) has been shown to involve a defined set of protein components. In addition, thephospholipid bilayer may also make a specific contribution to a functional ER integration site. This review focuses on recent studies of membrane protein insertion and subsequent maturation events, both of which are prerequisites for the synthesis of functional integral membrane proteins.