sec23

Sec23 is a core component of the COPII coat complex that drives vesicle budding from the endoplasmic reticulum (ER) to the Golgi apparatus. In most eukaryotes, Sec23 forms a heterodimer with Sec24 to constitute the inner COPII coat, which collaborates with the outer coat formed by Sec13 and Sec31 to assemble vesicles at ER exit sites. A key activity of Sec23 is to act as a GTPase-activating protein (GAP) for the small GTPase Sar1, stimulating GTP hydrolysis and promoting coat remodeling and vesicle scission after cargo capture.

Two vertebrate Sec23 paralogs exist: SEC23A and SEC23B. They share functional similarity but can differ in tissue distribution and specific roles in secretion. In many organisms, loss of Sec23 function is lethal, reflecting its essential role in ER-to-Golgi transport and overall secretory pathway integrity.

Genetic mutations in SEC23A and SEC23B are linked to human disease. SEC23A mutations cause cranio-lenticulo-skeletal dysplasia, a skeletal malformation syndrome, while SEC23B mutations cause congenital dyserythropoietic anemia type II, characterized by impaired red blood cell development.

In research contexts, Sec23 is studied to understand COPII coat assembly, cargo selection by Sec24, and regulation of ER exit site dynamics. It is a widely conserved component of the secretory pathway and serves as a foundational model for vesicle trafficking mechanisms.