'MitoCarta' maps out organelle

Scientists have gained several insights into the biological roles of proteins by creating the most comprehensive ‘parts list’ to date for mitochondria.

The MitoCarta is a ‘parts list’ of the constituents of mitochondria

Mitochondria - found within the cells of all eukaryotes from yeast to humans - are sub-cellular compartments well known for their role in providing cellular energy. They have also been implicated in a wide range of normal and disease processes, including diabetes.

“For years, a fundamental question in cell biology has gone largely unanswered - what proteins function in mitochondria?” said Vamsi Mootha, an associate member at the Broad Institute of MIT and Harvard, who led the study. “By creating a comprehensive list, we now have a valuable resource that has already helped enhance our understanding of mitochondrial biology and disease.”

Although mitochondria have their own genome - a vestige from their days as free-living bacteria - the vast majority of the critical mitochondrial proteins are derived from the nuclear genome. However, even with the wealth of genome sequence data now available, scientists have struggled to identify which genes encode the roughly 1,200 proteins that make up a functional mitochondrion.

As a result of their analyses, the researchers identified a total of 1,098 mitochondrial proteins to form a compendium they have named “MitoCarta” and which is available to the entire scientific community. Notably, say the team, about one-third of this inventory has not been previously linked to the organelle.

“The technologies and analytical methods for measuring proteins on a large scale are really transforming what we can learn about human biology,” said Steve Carr, director of the Proteomics Platform at the Broad Institute and a co-author of the Cell paper. “By applying them to mitochondria isolated from fourteen different mouse tissues, we’ve completed one of the most comprehensive proteomic analyses of any organelle to date.”