Protein import to mitochondria

Most mitochondrial proteins are synthesized in the cytosol as heavy precurs ors and then transported into mitochondria by a specific transport machiner y. Involved in this transport are the following protein components: cytosol ic chaperones, which bind to precursor proteins, receptors (protein subcomp lexes Tom37-Tom70 and Tom20-Tom22) localized on the outer mitochondrial mem brane, import channels in the outer (Tom40, Tom5, Tom6, and Tom7) and inner (Tim44, Tim23, and Tim17) mitochondrial membranes, and mitochondrial chape rones. The review considers the protein composition of the particular compo nents of the transport machinery, the principles of their functioning, and possible ways of sorting protein precursors according to their final destin ation. A new nomenclature of protein components involved in protein translo cation across mitochondrial membranes is compared to that in current use.