Protein folding in membranes

摘要

By virtue of their immersion into the hydrophobic membrane environment and the strong coupling between secondary structure formation and membrane partitioning, membrane proteins typically fold into extremely stable structures. Unlike the situation for water soluble proteins, the "denaturation" of membrane proteins by temperature, pH or chemical denaturants rarely leads to an unfolded protein chain. This means that equilibrium denaturation studies on membrane proteins are challenging in the laboratory and are rare in the literature. Thus, our understanding of the detailed principles of folding and unfolding of proteins in membranes is still fragmentary; only the parts of the folding/unfolding process that are amenable to experimental study are described in much detail. Many of the same issues are at play in the living cell where a series of special protein machines are essential for the sorting and folding of membrane proteins.