Microsomal triglyceride transfer protein large subunit is a protein that in humans is encoded by the MTTP, also known as MTP, gene.
MTTP encodes the large subunit of the heterodimeric microsomal triglyceride transfer protein (MTP). Protein disulfide isomerase (PDI) completes the heterodimeric MTP, which has been shown to play a central role in lipoprotein assembly. Mutations in MTTP can cause abetalipoproteinemia.
Apolipoprotein B48 on chylomicra and Apolipoprotein B100 on LDL, IDL, and VLDL are important for MTP binding.
MTP adds triglycerides to nascent chylomicrons in the intestine, and to VLDL in the liver.