Isolation and characterization of three endosomal fractions from the liver of estradiol-treated rats
Three distinct endosomal fractions were isolated in high purity from livers of estradiol-treated rats. Each fraction had characteristic physical and ultrastructural properties, but the lipid composition and major proteins of their membranes were similar and differed from those derived from the Golgi apparatus. Injected radioiodinated low density lipoproteins accumulated first in the fraction of intermediate density and later in the low density fraction. The latter was composed almost exclusively of lipoprotein-filled multivesicular bodies, most of which had a single membranous appendage. The fraction of intermediate density was composed of lipoprotein-filled vesicles that were smaller than multivesicular bodies and also had membranous appendages. The high density fraction was composed of membranes resembling the appendages of the two vesicular fractions. All three fractions were enriched in receptors for low density lipoproteins and asialoglycoproteins, but receptor concentrations were considerably reduced in multivesicular bodies. The fraction of intermediate density may represent the compartment of uncoupling of receptor and ligand (CURL) described by Geuze et al. CURL vesicles may lose some of their appendages as multivesicular bodies are formed. The high density fraction than may represent a receptor-recycling compartment.
- Research Organization:
- Univ. of California, San Francisco (USA)
- OSTI ID:
- 7143293
- Journal Information:
- Proc. Natl. Acad. Sci. U.S.A.; (United States), Vol. 84:19
- Country of Publication:
- United States
- Language:
- English
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CELL MEMBRANES
ENZYME ACTIVITY
LABELLED COMPOUNDS
UPTAKE
LIPOPROTEINS
ELECTROPHORESIS
ESTRADIOL
IODINE 125
LIVER
MONOCLONAL ANTIBODIES
PHAGOCYTOSIS
RATS
RECEPTORS
ANIMALS
ANTIBODIES
BETA DECAY RADIOISOTOPES
BODY
CELL CONSTITUENTS
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
ELECTRON CAPTURE RADIOISOTOPES
ESTRANES
ESTROGENS
GLANDS
HORMONES
HYDROXY COMPOUNDS
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPES
LIPIDS
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RADIOISOTOPES
RODENTS
STEROID HORMONES
STEROIDS
VERTEBRATES
550301* - Cytology- Tracer Techniques
550201 - Biochemistry- Tracer Techniques