Pathways and energetics of mitochondrial protein import in Saccharomyces cerevisiae

This chapter discusses the pathways and energetics of mitochondrial protein import in saccharomyces cerevisiae and the two methods that have proven useful for studying the mechanistic aspects of protein import. The first method is the subfractionation of the mitochondria to determine the location of an imported polypeptide. The second method involves the manipulation of adenosine triphosphate (ATP) levels both outside and inside the mitochondria. These procedures have been developed for studying mitochondria purified from the yeast saccharomyces cerevisiae. Various precursor proteins differ in their ATP requirements for import into isolated mitochondria. The chapter distinguishes between ATP that is outside the inner membrane (here referred to as external ATP) and ATP that is in the mitochondrial matrix. Some precursors require both external ATP and matrix ATP for efficient import; others require only external ATP or only matrix ATP, and some precursors require no ATP at all. © 1995 Elsevier Inc.