Beta-lipoproteins are involved in the transport of fats, cholesterol and fat soluble vitamins in the bloodstream. As fats and vitamins are essential to the development of cells and tissues, beta-lipoproteins play an essential physiological role in the body. MTTP is involved in the production of beta-lipoproteins by catalyzing the transport of cholesteryl ester, phospholipid and triglyceride from phospholipid surfaces.

Mutations in the MTTP gene have been associated with abetalipoproteinemia, a rare disorder characterized by the malabsorption of fats and lipid soluble vitamins resulting in hypocholesterolemia and vitamin deficiency. Mutations can result in the absence of the MTP protein or in a short non-functional version of it.

MTTP is located on the long arm of chromosome 4. The approximately 60 kb long gene is made up of 19 exons. MTTP encodes a 97 kDa large subunit that is 894 amino acids long. This subunit forms a heterodimer along with the protein disulfide isomerase.

More than 30 mutations in the MTTP gene have been linked to abetalipoproteinemia. Of these, the c.2593G-T transversion, which results in the replacement of glycine with a stop signal (G865X). The latter has been found to be more prevalent in Ashkenazi Jewish populations.