Protein Insertion Into The Outer Mitochondrial Membrane

Abstract

Biogenesis of the outer mitochondrial membrane (OMM) requires that cytoplasmically synthesized proteins be targeted to the organelle and selectively inserted into the outer membrane. Unlike most proteins of the mitochondrial matrix, inner mitochondrial membrane (IMM), and the intermembrane space (IMS), outer membrane proteins do not have cleavable N-terminal signal sequences and membrane insertion is independent of a transmembrane potential. In order to be correctly sorted, the protein must signal termination of translocation across the OMM and become stably integrated into the hydrophobic core of the phospholipid bilayer. Hydrophobic proteins of the IMM or matrix must be allowed to slip freely through the OMM. Protein receptors and components of the insertion machinery which interact specifically with OMM proteins remain largely uncharacterized. We are interested in the extent of overlap between the pathway of OMM insertion and import to the matrix or IMM and how this relates to proper sorting.