Yeast molecular chaperone gene SSB2 is involved in the endoplasmic reticulum stress response.

The Saccharomyces cerevisiae chaperone gene SSB2 belongs to the Hsp70 family. Unlike other HSP70 genes, SSB2 gene expression is reduced after heat shock. It has been reported that Ssb2p can be cross-linked to ribosome-bound nascent polypeptide chains, suggesting a potential role of SSB2 in the endoplasmic reticulum (ER) stress response.

PMT1 deficiency extends the shortened replicative lifespan of TED1-deficient yeast in a Hac1p-dependent manner.

Protein O-mannosyltransferase-1 (Pmt1p) deficiency extends the replicative lifespan (RLS) of Saccharomyces cerevisiae, which is related to the activation of the unfolded protein response (UPR), an important pathway for alleviating endoplasmic reticulum (ER) stress. Trafficking of Emp24p/Erv25p-dependent cargo disrupted 1 (Ted1p) has been reported as a binding partner of yeast Pmt1p. We explored the potential relationship between Pmt1p and Ted1p in the cell lifespan and ER stress responses.

Yeast polyubiquitin gene UBI4 deficiency leads to early induction of apoptosis and shortened replicative lifespan.

Ubiquitin is a 76-amino acid protein that is highly conserved among higher and lower eukaryotes. The polyubiquitin gene UBI4 encodes a unique precursor protein that contains five ubiquitin repeats organized in a head-to-tail arrangement. Although the involvement of the yeast polyubiquitin gene UBI4 in the stress response was reported long ago, there are no reports regarding the underlying mechanism of this involvement.