Acts as a molecular scaffold that plays a key role in the organization of the endoplasmic reticulum exit sites (ERES), also known as transitional endoplasmic reticulum (tER). SAR1A-GTP-dependent assembly of SEC16A on the ER membrane forms an organized scaffold defining an ERES. Required for secretory cargo traffic from the endoplasmic reticulum to the Golgi apparatus (PubMed:17428803). Mediates the recruitment of MIA3/TANGO to ERES. Regulates both conventional (ER/Golgi-dependent) and GORASP2-mediated unconventional (ER/Golgi-independent) trafficking of CFTR to cell membrane (By similarity). Acts as a RAB10 effector in the regulation of insulin-induced SLC2A4/GLUT4 glucose transporter-enriched vesicles delivery to the plasma membrane in adipocytes (PubMed:27354378). SEC16A and SEC16B are each present in multiple copies in a heteromeric complex (By similarity). Interacts with SEC23A (PubMed:17428803). Interacts with RNF183, RNF152, MIA3 and SEC13 (By similarity). Interacts with GORASP2 in response to ER stress (By similarity). Interacts with LRRK2 (via ROC domain) (PubMed:25201882). Interacts with RAB10 (PubMed:27354378). SAR1A activity is required to maintain SEC16A localization at discrete locations on the ER membrane perhaps by preventing its dissociation (By similarity). Localizes to endoplasmic reticulum exit sites (ERES), also known as transitional endoplasmic reticulum (tER). MIA3 and LRRK2 are required for its proper localization to ERES (PubMed:25201882). Recruited to microsomal membrane in SAR1-dependent manner (By similarity). Belongs to the SEC16 family.