Insulin Induced Gene 2 (INSIG2)

The gated movement of sterol regulatory element-binding proteins from the endoplasmic reticulum (ER) to the Golgi complex is the central event in lipid homeostasis in animal cells. SREBPs activate genes encoding enzymes required for synthesis of cholesterol, fatty acids, triglycerides, and phospholipids. In the presence of sterols, INSIG2 regulates lipid synthesis by blocking the proteolytic activation of SREBPs by SCAP and causing SREBPs to be retained in the ER.

INSIG2 is highly similar to the protein product encoded by gene INSIG1. Both INSIG1 protein and this protein are endoplasmic reticulum proteins that block the processing of sterol regulatory element binding proteins (SREBPs) by binding to SREBP cleavage-activating protein (SCAP), and thus prevent SCAP from escorting SREBPs to the Golgi.