TOBIOJ The Open Biology Journal Open Bio. J. 1874-1967 Bentham Open TOBIOJ-2-200 10.2174/1874196700902010200 Biology The Tightly Regulated and Compartmentalised Import, Sorting and Folding of Mitochondrial Proteins Cassina Laura Casari Giorgio * Neurogenomics Unit, Center for Genomics, Bioinformatics and Biostatistics, San Raffaele Scientific Institute and San Raffaele University, Milan, Italy Address correspondence to this author at the School of Medicine, San Raffaele University and San Raffaele Scientific Institute, Via Olgettina 58, 20132, Milan, Italy; Tel: +39 02 431; E-mail: casari.giorgio@hsr.it 31 12 2009 2009 2 200 221 06 05 2009 29 07 2009 12 08 2009 © 2009 Cassina and Casari 2009 Laura Cassina and Giorgio Casari

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Mitochondria are eukaryotic intracellular organelles that still bear the signatures of their prokaryotic ancestor and require nuclear assistance. They generously dispense energy to cells, but are also involved in several biosynthetic processes, as well as in cell signalling pathways and programmed cell death.

Mitochondria are partitioned into four intra-organelle compartments: the outer membrane, the inner membrane, the intermembrane space and the matrix. Each compartment contains a unique set of proteins and a personalised system for guaranteeing protein homeostasis.

What follows is a survey of the function and topology of the multiple systems that operate the concerted action of protein sorting and folding in the four mitochondrial compartments.

 Keywords Mitochondrial proteins mitochondrial proteins folding mitochondrial compartments mitochondrial protein sorting