MTTP (Microsomal Triglyceride Transfer Protein) is a crucial lipid transfer protein, responsible for transporting triglycerides, cholesterol, and other lipids from the liver and intestinal cells into the bloodstream, forming lipoprotein particles. MTTP is primarily expressed in the endoplasmic reticulum of the liver, intestines, and heart. It is essential for the formation of lipoproteins and the maintenance of plasma lipid levels. Mutations in the MTTP gene can lead to lipoprotein assembly disorder, such as familial hypobetalipoproteinemia, which is associated with an increased risk of cardiovascular diseases.