Targeting of tail-anchored proteins to yeast mitochondria in vivo

Tail-anchored proteins are inserted into intracellular membranes via a C-te rminal transmembrane domain. The topology of the protein is such that inser tion must occur posttranslationally, since the insertion sequence is not av ailable for membrane insertion until after translation of the tail-anchored polypeptide is completed. Here, we show that the targeting information in one such tail-anchored protein, translocase in the outer mitochondrial memb rane 22, is contained in a short region flanking the transmembrane domain. An equivalent region is sufficient to specify the localisation of Bcl2 and SNARE proteins to the secretory membranes. We discuss the targeting process for directing members of this protein family to the secretory and mitochon drial membranes in vivo. (C) 1999 Federation of European Biochemical Societ ies.