The function of MIA2 (MIA SH3 domain ER export factor 2, ENSG00000150527) is as follows. Plays a role in the transport of cargos that are too large to fit into COPII-coated vesicles and require specific mechanisms to be incorporated into membrane-bound carriers and exported from the endoplasmic reticulum (PubMed:21525241, PubMed:25202031, PubMed:27138255, PubMed:27170179). Plays a role in the secretion of lipoproteins, pre-chylomicrons and pre-VLDLs, by participating in their export from the endoplasmic reticulum (PubMed:27138255). Thereby, may play a role in cholesterol and triglyceride homeostasis (By similarity). Required for collagen VII (COL7A1) secretion by loading COL7A1 into transport carriers and recruiting PREB/SEC12 at the endoplasmic reticulum exit sites (PubMed:21525241, PubMed:25202031, PubMed:27170179). {ECO:0000250|UniProtKB:Q91ZV0, ECO:0000269|PubMed:21525241, ECO:0000269|PubMed:25202031, ECO:0000269|PubMed:27138255, ECO:0000269|PubMed:27170179}.