Determinants of the uptake of very low density lipoprotein remnants by the perfused rat liver

Journal Article · Sun Nov 01 04:00:00 EST 1987 · Metab., Clin. Exp.; (United States)

DOI:https://doi.org/10.1016/0026-0495(87)90034-5· OSTI ID:5786396

Arbeeny, C M; Rifici, V A; Handley, D A; Eder, H A

The receptor-mediated uptake of very low density lipoprotein (VLDL) remnants by the rat liver was studied. Livers were perfused with native /sup 125/I-VLDL remnants, radiolabeled apo E-deficient remnants, and radiolabeled remnants that contained reductively methylated apo B and unmodified apo E. The specific uptake of the apo E-deficient remnants was 20% of that for the native remnants, whereas the specific uptake of the remnants containing unreactive apo B was 78% of the control value. This suggests that the apo E of VLDL remnants is the principal ligand for binding to the receptor, and in the absence of apo E, apo B may participate in binding. This conclusion is supported by the finding that dimyristoyl phosphatidylcholine (DMPC)- apo E complexes were effective in competing for the hepatic uptake of /sup 125/I-VLDL remnants. The intracellular distribution of radioactivity was analyzed by Percoll density gradient centrifugation. At five minutes after perfusion, radioactivity was associated with the plasma membrane and lysosomal fractions, and at 30 minutes most of the radioactivity was associated with the lysosomal fraction. Binding and internalization of VLDL remnants was also directly visualized by electron microscopy. Internalization proceeded by coated pit-coated vesicle formation with subsequent delivery to lysosomes. Our findings demonstrate that the apo E of VLDL remnants mediates binding to the hepatic receptor and that the internalization and degradation of VLDL remnants is by a similar pathway to that previously described for LDL.

• Research Organization: Albert Einstein College of Medicine, Bronx, NY
• OSTI ID: 5786396
• Journal Information: Metab., Clin. Exp.; (United States), Journal Name: Metab., Clin. Exp.; (United States) Vol. 36:11; ISSN METAA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL PATHWAYS
BODY
CELL CONSTITUENTS
CELL MEMBRANES
CENTRIFUGATION
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
ELECTRON CAPTURE RADIOISOTOPES
ELECTRON MICROSCOPY
GLANDS
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIPIDS
LIPOPROTEINS
LIVER
LYSOSOMES
MAMMALS
MEMBRANE PROTEINS
MEMBRANE TRANSPORT
MEMBRANES
MICROSCOPY
MOLECULAR WEIGHT
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANOIDS
ORGANS
PERFUSED ORGANS
PROTEINS
RADIOISOTOPES
RATS
REACTION KINETICS
RECEPTORS
RODENTS
SEPARATION PROCESSES
TRACER TECHNIQUES
ULTRACENTRIFUGATION
VERTEBRATES