MIA3 (MIA SH3 domain ER export factor 3) is a specialized cargo receptor protein that facilitates the export of large proteins from the endoplasmic reticulum (ER) that cannot fit into standard COPII-coated vesicles. MIA3 specifically mediates the secretion of collagen VII (COL7A1) by loading it into transport carriers and binding to COPII coat subunits Sec23/24 to guide cargo into growing carriers 1. The protein also participates in lipoprotein transport and is required for correct assembly of COPII coat components at ER exit sites 1. MIA3 demonstrates significant disease relevance, particularly in cardiovascular pathology. Genetic variants in MIA3 are associated with coronary artery disease (CAD) risk across multiple populations 2. The protein regulates vascular smooth muscle cell (VSMC) proliferation, with higher MIA3 expression promoting atheroprotective VSMC phenotypes essential for protective fibrous cap formation 3. MIA3 also participates in a molecular signaling network with ADTRP through PI3K/AKT pathways, influencing endothelial cell functions relevant to atherosclerosis 1. Clinically, MIA3 mutations cause odontochondrodysplasia and have been implicated in Ehlers-Danlos-like syndromes due to disrupted collagen transport 4. Additionally, MIA3 shows oncogenic properties in hepatocellular carcinoma by promoting glutathione degradation through CHAC1 binding 5.