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:17192411, PubMed:17005010, PubMed:17428803, PubMed:21768384, PubMed:22355596). Mediates the recruitment of MIA3/TANGO to ERES (PubMed:28442536). Regulates both conventional (ER/Golgi-dependent) and GORASP2-mediated unconventional (ER/Golgi-independent) trafficking of CFTR to cell membrane (PubMed:28067262). Positively regulates the protein stability of E3 ubiquitin-protein ligases RNF152 and RNF183 and the ER localization of RNF183 (PubMed:29300766). Acts as a RAB10 effector in the regulation of insulin-induced SLC2A4/GLUT4 glucose transporter-enriched vesicles delivery to the cell membrane in adipocytes (By similarity). SEC16A and SEC16B are each present in multiple copies in a heteromeric complex (PubMed:17192411, PubMed:22355596). Interacts with SEC23A (PubMed:17192411, PubMed:17428803). Interacts with RNF183 and RNF152 (PubMed:29300766). Interacts with LRRK2 (via ROC domain) (PubMed:25201882). Interacts with SEC13 (PubMed:25201882, PubMed:19638414, PubMed:17428803). Interacts with RAB10 (By similarity). Interacts with MIA3 (PubMed:28442536). Interacts with GORASP2 in response to ER stress (PubMed:28067262). SAR1A activity is required to maintain SEC16A localization at discrete locations on the ER membrane perhaps by preventing its dissociation (PubMed:17192411). 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, PubMed:28442536, PubMed:19638414, PubMed:17428803, PubMed:22355596). Recruited to microsomal membrane in SAR1-dependent manner (PubMed:17428803). Ubiquitous. Expressed at higher levels in the pancreas. Belongs to the SEC16 family. Extended N-terminus.