I recently evaluated this paper for F1000 Prime.
Sec23 homolog Nel1 is a novel GTPase-activating protein for Sar1 but does not function as a subunit of the COPII coat.
This paper suggests a possible mechanism by which the Sar1 GTP-binding protein is kept inactive outside of the context of the COPII coat. The work provides a relatively straightforward characterization of the Nel1 gene product in Saccharomyces cerevisiae. COPII vesicles bud from the endoplasmic reticulum (ER) to drive the first membrane trafficking step in the eukaryotic secretory pathway. The process is driven by activation of the small GTP-binding protein Sar1. A key feature of COPII assembly is spatial and temporal control. The most important findings are that it can act as a GTPase-activating protein for Sar1 and that it is not a component of the COPII coat. These data suggest that Nel1 could act to maintain Sar1 in an inactive state outside of the context of COPII vesicle budding. Whether Nel1 has roles (such as in signalling) outside of the context of COPII regulation remains to be defined.
This evaluation was originally published on Faculty of 1000 Prime.