Sec23p

Sec23p is a protein component of the COPII coat complex, which is essential for the formation of transport vesicles budding from the endoplasmic reticulum (ER) in eukaryotic cells. Along with Sec24p, it forms the inner layer of the COPII coat. This complex plays a crucial role in the selective cargo selection and membrane deformation required for the budding process. Sec23p possesses GTPase activating protein (GAP) activity for the small GTPase Sar1p, a key regulator of COPII assembly. This GAP activity is vital for hydrolyzing GTP bound to Sar1p, leading to Sar1p inactivation and the disassembly of the COPII coat after vesicle formation. The interaction of Sec23p with specific cargo molecules, often mediated by Sec24p, ensures that desired proteins and lipids are efficiently packaged into nascent vesicles for transport to the Golgi apparatus. Mutations in Sec23p can lead to defects in ER export, causing ER stress and various cellular dysfunctions. Its fundamental role in protein trafficking makes Sec23p a critical subject in cell biology research.