The Alb3/Oxa1/YidC protein family: membrane-localized chaperones facilitating membrane protein insertion?

The recently identified Alb3/Oxa1/YidC family constitutes a novel class of proteins that function in promoting membrane insertion in chloroplasts, mitochondria and bacteria. These proteins mediate membrane insertion of a diverse group of membrane proteins that range from phage coat proteins in bacteria and respiratory-chain protein subunits in mitochondria to the light-harvesting chlorophyll-binding proteins in chloroplasts. Here, we discuss the Alb3/Oxa1/YidC protein family and their possible function as membrane chaperones, helping newly synthesized proteins to fold into the membrane bilayer.