CO-TRANSLATIONAL PROTEIN IMPORT INTO MITOCHONDRIA - AN ALTERNATIVE VIEW

Recent in vitro and in vivo experiments suggest that the synthesis and import of mitochondrial proteins are very tightly coupled and that a co-translational import reaction may be mandatory for some proteins. T hese results are entirely consistent with early experiments which sugg ested that import occurs co-translationally and that cytosolic polysom es synthesizing mitochondrial proteins are bound to protein import sit es on isolated mitochondria. This article discusses the seemingly cont radictory reports concerning the involvement of co-translational and p ost-translational mechanisms in the import process and examines the im pact of recent developments in the field.