The nutrient stress-induced small GTPase Rab5 contributes to the activation of vesicle trafficking and vacuolar activity.

Rab family small GTPases regulate membrane trafficking by spatiotemporal recruitment of various effectors. However, it remains largely unclear how the expression and functions of Rab proteins are regulated in response to extracellular or intracellular stimuli. Here we show that Ypt53, one isoform of Rab5 in Saccharomyces cerevisiae, is up-regulated significantly under nutrient stress.

The Role of Elongin BC-Containing Ubiquitin Ligases.

The Elongin complex was originally identified as a positive regulator of RNA polymerase II and is composed of a transcriptionally active subunit (A) and two regulatory subunits (B and C). The Elongin BC complex enhances the transcriptional activity of Elongin A. "Classical" SOCS box-containing proteins interact with the Elongin BC complex and have ubiquitin ligase activity.