Inactivation of the endoplasmic reticulum protein translocation factor, Sec61p, or its homolog, Ssh1p, does not affect peroxisome biogenesis.

Preferential Targeting of a Signal Recognition Particle-dependent Precursor to the Ssh1p Translocon in Yeast♦

Protein translocation across the endoplasmic reticulum membrane occurs via a "translocon" channel formed by the Sec61p complex. In yeast, two channels exist: the canonical Sec61p channel and a homolog called Ssh1p. Here, we used trapped translocation intermediates to demonstrate that a specific signal recognition particle-dependent substrate, Sec71p, is targeted exclusively to Ssh1p. Strikingly...

Recognition of a subset of signal sequences by Ssh1p, a Sec61p-related protein in the membrane of endoplasmic reticulum of yeast Saccharomyces cerevisiae.

Ssh1p of Saccharomyces cerevisiae is related in sequence to Sec61p, a general receptor for signal sequences and the major subunit of the channel that guides proteins across the membrane of the endoplasmic reticulum. The split-ubiquitin technique was used to determine whether Ssh1p serves as an additional receptor for signal sequences in vivo. We measured the interactions between the N(ub)-label...

Recognition of a subset of signal sequences by Ssh1p, a Sec61p related protein in the membrane of the endoplasmic reticulum of the yeast S. cerevisiae

Evolutionarily conserved binding of ribosomes to the translocation channel via the large ribosomal RNA.

During early stages of cotranslational protein translocation across the endoplasmic reticulum (ER) membrane the ribosome is targeted to the heterotrimeric Sec61p complex, the major component of the protein-conducting channel. We demonstrate that this interaction is mediated by the 28S rRNA of the eukaryotic large ribosomal subunit. Bacterial ribosomes also bind via their 23S rRNA to the bacteri...

Interactions between Sec complex and prepro-alpha-factor during posttranslational protein transport into the endoplasmic reticulum.

Posttranslational translocation of prepro-alpha-factor (ppalphaF) across the yeast endoplasmic reticulum membrane begins with the binding of the signal sequence to the Sec complex, a membrane component consisting of the trimeric Sec61p complex and the tetrameric Sec62p/63p complex. We show by photo-cross-linking that the signal sequence is bound directly to a site where it contacts simultaneous...