A gating motif in the translocation channel sets the hydrophobicity threshold for signal sequence function.

ABSTRACT: A critical event in protein translocation across the endoplasmic reticulum is the structural transition between the closed and open conformations of Sec61, the eukaryotic translocation channel. Channel opening allows signal sequence insertion into a gap between the N- and C-terminal halves of Sec61. We have identified a gating motif that regulates the transition between the closed and open channel conformations. Polar amino acid substitutions in the gating motif cause a gain-of-function phenotype that permits translocation of precursors with marginally hydrophobic signal sequences. In contrast, hydrophobic substitutions at certain residues in the gating motif cause a protein translocation defect. We conclude that the gating motif establishes the hydrophobicity threshold for functional inse

SUBMITTER: Trueman SF 

PROVIDER: S-EPMC3518225 | biostudies-literature | 2012 Dec

REPOSITORIES: biostudies-literature