Biogenesis of Cytochrome Oxidase and Cytochrome b in Neurospora crassa

Abstract

In this article we would like to outline the close cooperation between the mitochondrial and cytoplasmic protein-synthesizing systems in mitochondrial biogenesis. The subject of our studies is two proteins of the mitochondrial membrane, cytochrome oxidase and cytochrome b. We will give a concise survey of our own experimental results and of the concepts we have formed during recent years of investigation on the fungus Neurospora crassa. In this chapter we will describe first the procedures for selective labeling of mitochondrial proteins according to their site of biosynthesis (either the mitochondrial or the nucleocytoplasmic-translation system). Secondly, we will describe techniques for the separation of the radioactively-labeled mitochondrial membrane proteins and the subsequent purification of cytochrome oxidase and cytochrome b. We will report on a new chromatographic system for the purification of mitochondrial membrane proteins which we believe to be applicable to a wider range of biological membranes. We will then review results on the molecular structure and biogenesis of cytochrome oxidase and cytochrome b and conclude by discussing our results together with those of other groups with regard to mitochondrial biogenesis in general.