Evolutionary conservation of components of the protein translocation complex.
Protein translocation into the mammalian endoplasmic reticulum requires the Sec61p complex, which consists of three membrane proteins. The alpha-subunit, the homologue of Sec61p of yeast, shows some similarity to SecYp, a key component of the protein export apparatus of bacteria. In Escherichia coli, SecYp is also associated with two other proteins (SecEp and band-1 protein). We have now determined the sequences of the beta- and gamma-subunits of the mammalian Sec61p complex. Sec61-gamma is homologous to SSS1p, a suppressor of sec61 mutants in Saccharomyces cerevisiae, and can functionally replace it in yeast cells. Moreover, Sec61-gamma and SSS1p are structurally related to SecEp of E. coli and to putative homologues in various other bacteria. At least two subunits of the Sec61/SecYp complex therefore seem to be key components of the protein translocation apparatus in all classes of organisms.
Hartmann
E
E
Max-Delbrück Centre for Molecular Medicine, Berlin-Buch, Germany.
Sommer
T
T
Prehn
S
S
Görlich
D
D
Jentsch
S
S
Rapoport
T A
TA
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001692:Biological Transport / Q000502:physiology; D017124:Conserved Sequence; D004285:Dogs; D005057:Eukaryotic Cells / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics* / Q000502:physiology; D008969:Molecular Sequence Data; D009154:Mutation; D011387:Prokaryotic Cells / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D000069816:SEC Translocation Channels; D017386:Sequence Homology, Amino Acid
D008565:Membrane Proteins; D011506:Proteins; D000069816:SEC Translocation Channels; C000613244:SEC61A1 protein, human; C499388:SEC61B protein, human; C499389:SEC61G protein, human