Evolutionary conservation of components of the protein translocation complex

Enno Hartmann, Thomas Sommer, Siegfried Prehn, Dirk Görlich, Stefan Jentsch, Tom A. Rapoport*

*Corresponding author for this work
190 Citations (Scopus)


PROTEIN translocation into the mammalian endoplasmic reticulum requires the Sec61p complex, which consists of three membrane proteins1. The α-subunit, the homologue of Sec61p of yeast2-4, shows some similarity to SecYp5, a key component of the protein export apparatus of bacteria6,7. In Escherichia coli, SecYp is also associated with two other proteins (SecEp and band-1 protein)8,9. We have now determined the sequences of the β- and γ-subunits of the mammalian Sec61p complex. Sec61-γ is homologous to SSSlp, a suppressor of sec61 mutants in Saccharomyces cerevisiae, and can functionally replace it in yeast cells. Moreover, Sec61-γ and SSSlp are structurally related to SecEp of E. coli and to putative homologues in various other bacteria. At least two sub-units of the Sec61/SecYp complex therefore seem to be key components of the protein translocation apparatus in all classes of organisms.

Original languageEnglish
Issue number6464
Pages (from-to)654-657
Number of pages4
Publication statusPublished - 01.12.1994


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