PMID:15851514
| Citation |
Cannon, KS, Or, E, Clemons, WM Jr, Shibata, Y and Rapoport, TA (2005) Disulfide bridge formation between SecY and a translocating polypeptide localizes the translocation pore to the center of SecY. J. Cell Biol. 169:219-25 |
|---|---|
| Abstract |
During their biosynthesis, many proteins pass through the membrane via a hydrophilic channel formed by the heterotrimeric Sec61/SecY complex. Whether this channel forms at the interface of multiple copies of Sec61/SecY or is intrinsic to a monomeric complex, as suggested by the recently solved X-ray structure of the Methanococcus jannaschii SecY complex, is a matter of contention. By introducing a single cysteine at various positions in Escherichia coli SecY and testing its ability to form a disulfide bond with a single cysteine in a translocating chain, we provide evidence that translocating polypeptides pass through the center of the SecY complex. The strongest cross-links were observed with residues that would form a constriction in an hourglass-shaped pore. This suggests that the channel makes only limited contact with a translocating polypeptide, thus minimizing the energy required for translocation. |
| Links |
PubMed PMC2171872 Online version:10.1083/jcb.200412019 |
| Keywords |
Amino Acid Substitution; Crystallography, X-Ray; Cysteine/chemistry; Disulfides/chemistry; Escherichia coli/chemistry; Escherichia coli/physiology; Escherichia coli Proteins/chemistry; Peptides/chemistry; Protein Structure, Quaternary; Protein Structure, Secondary; Protein Transport/physiology |
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