Functions as a component of the nuclear pore complex (NPC) and the COPII coat (PubMed:8972206). At the endoplasmic reticulum, SEC13 is involved in the biogenesis of COPII-coated vesicles (PubMed:8972206). Required for the exit of adipsin (CFD/ADN), an adipocyte-secreted protein from the endoplasmic reticulum (By similarity). {ECO:0000250|UniProtKB:Q9D1M0, ECO:0000269|PubMed:8972206}. As a component of the GATOR2 complex, functions as an activator of the amino acid-sensing branch of the mTORC1 signaling pathway (PubMed:23723238, PubMed:25457612, PubMed:27487210, PubMed:35831510, PubMed:36528027). The GATOR2 complex indirectly activates mTORC1 through the inhibition of the GATOR1 subcomplex (PubMed:23723238, PubMed:27487210, PubMed:35831510, PubMed:36528027). GATOR2 probably acts as an E3 ubiquitin-protein ligase toward GATOR1 (PubMed:36528027). In the presence of abundant amino acids, the GATOR2 complex mediates ubiquitination of the NPRL2 core component of the GATOR1 complex, leading to GATOR1 inactivation (PubMed:36528027). In the absence of amino acids, GATOR2 is inhibited, activating the GATOR1 complex (PubMed:25457612, PubMed:26972053, PubMed:27487210). Within the GATOR2 complex, SEC13 and SEH1L are required to stabilize the complex (PubMed:35831510). {ECO:0000269|PubMed:23723238, ECO:0000269|PubMed:25457612, ECO:0000269|PubMed:26972053, ECO:0000269|PubMed:27487210, ECO:0000269|PubMed:35831510, ECO:0000269|PubMed:36528027}. This is the function of SEC13 (SEC13 homolog, nuclear pore and COPII component, Ensembl gene identifier ENSG00000157020).