Mitochondrial contact sites as platforms for phospholipid exchange

• Homeostasis of mitochondrial phospholipids depends on membrane contact sites.
• ERMES complex is the first system shown to be involved in mitochondrial glycerophospholipid exchange with other organelles.
• ERMES subunits actively bind lipid molecules for transport.
• ERMES-independent pathways contribute to exchange of lipids between mitochondria and other cellular compartments.

Mitochondria are unique organelles that contain their own – although strongly reduced – genome, and are surrounded by two membranes. While most cellular phospholipid biosynthesis takes place in the ER, mitochondria harbor the whole spectrum of glycerophospholipids common to biological membranes. Mitochondria also contribute to overall phospholipid biosynthesis in cells by producing phosphatidylethanolamine, phosphatidylglycerol, and cardiolipin. Considering these features, it is not surprising that mitochondria maintain highly active exchange of phospholipids with other cellular compartments. In this contribution we describe the transport of phospholipids between mitochondria and other organelles, and discuss recent developments in our understanding of the molecular functions of the protein complexes that mediate these processes. This article is part of a Special Issue entitled: Lipids of Mitochondria edited by Guenther Daum.