The transport of proteins from the endoplasmic reticulum to the Golgi requires the assembly of a Coat Protein II (COPII) complex at certain sites on the membrane. These are known as endoplasmic reticulum exit sites (ERES) or transitional ER sites. The SEC16A gene encodes a peripheral membrane protein that is responsible for COPII vesicles coating, defining the transitional ER sites, endoplasmic reticulum organization and regulating secretory cargo traffic from the endoplasmic reticulum to the Golgi apparatus. The protein is recruited to the ER membrane by SAR1 and it has been found to interact with the COPII components SEC23A and SEC13.

The SEC16A gene is located on the long arm of chromosome 9. It spans a length of 44.4 kb of DNA and its coding sequence is spread across 37 exons. The gene encodes a 233.5 kDa protein product composed of 2179 amino acids. Several additional isoforms of the SEC16A protein exist due to alternatively spliced transcript variants. While the gene is ubiquitously expressed in the human body, overexpression is seen in the bone, bone marrow stromal cells, peripheral blood mononuclear cells and pancreas.