Ta. Rapoport et al., PROTEIN-TRANSPORT ACROSS THE EUKARYOTIC ENDOPLASMIC-RETICULUM AND BACTERIAL INNER MEMBRANES, Annual review of biochemistry, 65, 1996, pp. 271-303
Protein transport across the endoplasmic reticulum membrane can occur
by two pathways, a co- and a post-translational one. In both cases, po
lypeptides are first targeted to translocation sites in the membrane b
y virtue of their signal sequences and then transported across or inse
rted into the phospholipid bilayer, most likely through a protein-cond
ucting channel. Key components of the translocation apparatus have now
been identified and the translocation pathways seem likely to be rela
ted to each other but mechanistically distinct. Protein transport acro
ss the bacterial inner membrane is both similar to and different from
the process in eukaryotes. Other pathways of protein translocation exi
st that bypass the ones involving classical signal sequences.