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Mitochondria; Import motor; Protein import; Signal sequence; TOM complex; TIM23 complex
Abstract:
Most mitochondrial proteins are encoded in the nucleus. They are synthesized as precursor forms in the
cytosol and must be imported into mitochondria with the help of different protein translocases. Distinct
import signals within precursors direct each protein to the mitochondrial surface and subsequently onto
specific transport routes to its final destination within these organelles. In this review we highlight common
principles of mitochondrial protein import and address different mechanisms of protein integration into
mitochondrial membranes. Over the last years it has become clear that mitochondrial protein translocases
are not independently operating units, but in fact closely cooperate with each other. We discuss recent studies
that indicate how the pathways for mitochondrial protein biogenesis are embedded into a functional network
of various other physiological processes, such as energy metabolism, signal transduction, and maintenance of
mitochondrial morphology. This article is part of a Special Issue entitled: Protein Import and Quality Control in
Mitochondria and Plastids.