Mouse microsomal triglyceride transfer protein large subunit: cDNA cloning, tissue-specific expression and chromosomal localization.

Abstract

Microsomal triglyceride transfer protein (MTP) catalyzes the transfer of triglyceride, cholesteryl ester, and phospholipid between membranes. It is essential for the secretion of apolipoprotein B from the cell. Mutations in MTP are a major cause of abetalipoproteinemia. The mouse is a popular animal model for lipoprotein metabolism. We have cloned and sequenced mouse MTP cDNA. The DNA-deduced amino acid sequence indicates that mouse MTP contains 894 amino acids; the mouse protein shows 93, 86, and 83% sequence identity to the hamster, human, and bovine sequences, respectively. Northern blot analysis indicates that mouse MTP mRNA is expressed at high levels in the small intestine and at substantially lower levels in the liver and that it is not detectable in six other tissues examined. The mouse MTP gene has been localized to the distal region of chromosome 3 by Southern blots of interspecific backcross panels using progeny derived from matings of (C57BL/6J x SPRET/Ei)F1 x SPRET/Ei. Comparison of MTP sequences from human, bovine, hamster, and mouse indicates that the C-terminal region of MTP is better conserved than its N-terminal region.