The Tightly Regulated and Compartmentalised Import, Sorting and Folding of Mitochondrial Proteins

Laura Cassina, Giorgio Casari*
Neurogenomics Unit, Center for Genomics, Bioinformatics and Biostatistics, San Raffaele Scientific Institute and San Raffaele University, Milan, Italy

© 2009 Cassina and Casari

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: ( This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* 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:


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.