Resolution of mitochondrial and chloroplast membrane protein complexes from green leaves of potato on blue-native polyacrylamide gels

Abstract

<span style="font-size:14.0pt;font-family:HiddenHorzOCR;mso-bidi-font-family:HiddenHorzOCR">Purification of mitochondria and mitochondrial protein complexes from green tissues is often severely impaired by the presence of chloroplasts and their proteins. Here we present a method which allows analysis of respiratory protein complexes from potato leaves. The procedure includes the preparation of an organellar fraction specifically enriched in &nbsp;mitochondria and the separation of organellar protein complexes by blue-native polyacrylamide gel electrophoresis (BN-PAGE). For the first time mitochondrial and chloroplast protein complexes have been resolved simultaneously in a native gel. BNPAGE allowed the separation of eleven bands, including the mitochondrial NADH-dehydrogenase, the bc₁ complex and the mitochondrial F₁-ATP synthase as well as the chloroplast F₁-ATP synthase, the cytochrome b₆f complex, the two photosystems and the light harvesting complex. The resolution of the protein complexes in the first dimension was good enough to allow identification of all subunits of individual complexes in the second dimension under denaturing conditions. Thus, BNPAGE offers an opportunity to analyze mitochondrial and chloroplast protein complexes from a single preparation from

very small amounts of tissue. The implications of our findings, for studies on protein expression and turnover in different tissues and developmental stages, are discussed.

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