Component of the coat protein complex II (COPII) which promotes the formation of transport vesicles from the endoplasmic reticulum (ER). The coat has two main functions, the physical deformation of the endoplasmic reticulum membrane into vesicles and the selection of cargo molecules for their transport to the Golgi complex. COPII is composed of at least five proteins: the Sec23/24 complex, the Sec13/31 complex and Sar1 (By similarity). Interacts with SAR1A (PubMed:26522472). Ubiquitously expressed. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. Belongs to the SEC23/SEC24 family. SEC23 subfamily.