INSIG1 (Insulin-Induced Gene 1): INSIG1 is a protein encoded by the INSIG1 gene, which plays a pivotal role in the regulation of lipid metabolism and cholesterol homeostasis within cells. It functions as a key mediator of the feedback inhibition loop that controls the synthesis and uptake of cholesterol. INSIG1 acts by binding to and inhibiting the activation of sterol regulatory element-binding proteins (SREBPs), which are transcription factors crucial for the expression of genes involved in cholesterol and fatty acid biosynthesis. By modulating SREBP activity, INSIG1 helps maintain cellular lipid levels within a tight physiological range, preventing excessive accumulation of cholesterol...