The role of lipids in the biogenesis of integral membrane proteins.

Most integral membrane proteins are cotranslationally inserted into the lipid bilayer. In prokaryotes, membrane insertion of the nascent chain takes place at the plasma membrane, whereas in eukaryotes insertion takes place into the endoplasmatic reticulum. In both kingdoms of life, however, the same membrane that acquaints the newly born membrane protein also synthesizes the bilayer lipids and thus ensures the balanced growth of the membrane as a whole. Recent evidence indicates that the lipid composition of the host membrane can determine the fate of the newborn membrane protein, as it can affect (1) the efficiency of translocation, (2) the topology of the resulting membrane protein, (3) its stability, (4) its assembly into oligomeric complexes, (5) its transport and sorting along the secretory pathway, and (6) its enzymatic activity. The lipid composition of the membrane thus can affect the biogenesis and function of integral membrane proteins at multiple steps along its biogenetic pathway. While understanding this interdependence between bilayer lipids and protein biogenesis is interesting in its own right, careful consideration of a potential host's membrane lipid composition may also allow optimization of the yield and activity of membrane proteins that are expressed in a heterologous organism. Here, we review and discuss some examples that illustrate the interdependence between bilayer lipids and the biogenesis of integral membrane proteins.