Sec12p

Sec12p is a protein involved in the secretory pathway of eukaryotic cells. It is a type II transmembrane protein localized to the endoplasmic reticulum (ER) membrane. Sec12p plays a crucial role in the formation of COPII-coated vesicles, which are essential for the transport of proteins and lipids from the ER to the Golgi apparatus.

Specifically, Sec12p functions as a guanine nucleotide exchange factor (GEF) for the small GTPase Sar1. It promotes the exchange of GDP for GTP on Sar1, thereby activating Sar1. Activated Sar1 then recruits other COPII coat proteins to the ER membrane, initiating the budding of vesicles. This process is vital for maintaining the integrity and function of the secretory pathway.

Mutations or defects in Sec12p can lead to a buildup of unfolded proteins in the ER, a condition known as ER stress. This can have significant consequences for cellular health and function, and has been implicated in various diseases. Research into Sec12p and its role in COPII vesicle formation continues to shed light on the intricate mechanisms of protein trafficking within the cell.