Reactome | MTTP lipidates APOB-100, forming a pre-VLDL

MTTP lipidates APOB-100, forming a pre-VLDL

Stable Identifier

R-HSA-8866329

Type

Reaction [transition]

Species

Homo sapiens

Compartment

endoplasmic reticulum lumen, endoplasmic reticulum membrane

ReviewStatus

5/5

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MTTP lipidates APOB-100, forming a pre-VLDL

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The assembly of very low-density lipoprotein (VLDL) occurs in two steps (Olofsson et al. 2000). In the first step, apolipoprotein B-100 (APOB(28-4563), APOB-100) is co- and post-translationally lipidated by MTP (microsomal triacylglycerol transfer protein) in the form of a MTP:PDI (protein disulfide isomerase) heterodimer (Gordon et al. 1995), forming a pre-VLDL. This occurs in the rough endoplasmic reticulum (RER) lumen. The pre-VLDL is loosely associated with the RER membrane. MTP in vitro binds small amounts of PL and TAG (annotated here as one molecule of each) and efficiently transfers the bound lipid between membranes (Atzel & Wetterau 1994). In vivo, MTP:PDI directly interacts with APOB-100 polypeptide (Wu et al. 1996), and is thought to transfer lipid from the endoplasmic reticulum membrane to nascent APOB-100. In humans, APOB-100 is expressed in the liver and forms VLDL whereas APOB-48 is expressed in the intestine and forms chylomicrons.

Literature References

PubMed ID	Title	Journal	Year
11369260	Intracellular assembly of VLDL: two major steps in separate cell compartments Olofsson, SO, Stillemark-Billton, P, Asp, L	Trends Cardiovasc. Med.	2000
7803401	Identification of two classes of lipid molecule binding sites on the microsomal triglyceride transfer protein Atzel, A, Wetterau, JR	Biochemistry	1994
14732096	Microsomal triglyceride transfer protein: a protein complex required for the assembly of lipoprotein particles Gordon, DA, Wetterau, JR, Gregg, RE	Trends Cell Biol	1995
8626595	Demonstration of a physical interaction between microsomal triglyceride transfer protein and apolipoprotein B during the assembly of ApoB-containing lipoproteins Wu, X, Zhou, M, Huang, LS, Wetterau, JR, Ginsberg, HN	J Biol Chem	1996