Uptake and intracellular fate of ( sup 14 C)sucrose-insulin in perfused rat livers
- Pennsylvania State Univ., Hershey (USA) Univ. of Texas Health Sciences Center, San Antonio (USA)
Insulin was covalently linked to ({sup 14}C)sucrose by means of cyanuric chloride to provide a label that would remain entrapped within the vacuolar system. The uptake of the conjugate by the perfused rat liver was rapid, competitively inhibited by native insulin, and abolished by alkali denaturation. As assessed by its distribution on self-generating gradients of colloidal silica-povidone, label in lysosome-enriched samples of liver taken at different times after the addition of the conjugate moved progressively during 15 min from the plasma membrane into an intermediate peak and then to dense lysosomal fractions. After 30-60 min, the label had equilibrated throughout the lysosomal-vacuolar system. The initial movement from the plasma membrane to the intermediate peak occurred between 2 and 5 min. Because label in the peak could be physically separated from the lysosomal marker, {beta}-acetylglucosaminidase, by dispersing the sample through the gradient mixture before centrifugation rather than layering it, the authors concluded that the intermediate particles in question were not lysosomal in nature. On gel-filtration chromatography, label extracted from the intermediate peak did not move with insulin but rather as a broad band of lower molecular weight products, suggesting that insulin is subject to early proteolytic attack within a nonlysosomal compartment.
- OSTI ID:
- 6828685
- Journal Information:
- American Journal of Physiology; (USA), Vol. 255:1; ISSN 0002-9513
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CARBON 14 COMPOUNDS
UPTAKE
INSULIN
BIODEGRADATION
CROSS-LINKING
SACCHAROSE
BIOCHEMICAL REACTION KINETICS
CELL MEMBRANES
CYANIDES
GLYCOSYL HYDROLASES
LIVER
LYSOSOMES
PERFUSED TISSUES
RATS
ANIMAL TISSUES
ANIMALS
BODY
CARBOHYDRATES
CELL CONSTITUENTS
CHEMICAL REACTIONS
DECOMPOSITION
DIGESTIVE SYSTEM
DISACCHARIDES
ENZYMES
GLANDS
HORMONES
HYDROLASES
KINETICS
LABELLED COMPOUNDS
MAMMALS
MEMBRANES
OLIGOSACCHARIDES
ORGANIC COMPOUNDS
ORGANOIDS
ORGANS
PEPTIDE HORMONES
POLYMERIZATION
REACTION KINETICS
RODENTS
SACCHARIDES
TISSUES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques