GTP-binding protein SAR1a (Sar1a)

Involved in transport from the endoplasmic reticulum to the Golgi apparatus. Required to maintain SEC16A localization at different locations on the ER membrane maybe by preventing its dissociation.

SAR1A-GTP-dependent gathering of SEC16A on the ER membrane forms an organized scaffold defining endoplasmic reticulum exit sites (ERES) (By similarity). .