Fig. 3.

Plasma membrane proteins broadly contaminate semipure mitochondria. (A) Western blots show the presence or absence of solute carriers and ion channels with known membrane transporter functions in ultrapure brain mitochondria preparations isolated by continuous density gradient ultracentrifugation. The canonical localization of selected proteins is color coded to the left of the blots as cytosol (white), PM (teal), ER (blue), MAM (pink), OMM (light gray), IMM (black), and mitochondrial matrix (dark gray) (n = 4, combined from two experiments). (B) Z score of relative levels of marker enrichment in ultrapure mitochondria fraction. Highest enrichment fractions are outlined in bold (n = 2). (C) Comparative localization with published, Gene Ontology, MitoCarta, and Uniprot references with mitochondrial assignment shown by gray shading. Database-reported mitochondrial localization that was not reproduced in these experiments is outlined by yellow, dashed lines.