Internalized insulin-receptor complexes are unidirectionally translocated to chloroquine-sensitive degradative sites. Dependence on metabolic energy

Journal Article · Mon Apr 25 04:00:00 EDT 1988 · J. Biol. Chem.; (United States)

OSTI ID:7191926

Berhanu, P

Insulin receptors on the surface of isolated rat adipocytes were photoaffinity labeled at 12 degrees C with the iodinated photoreactive insulin analogue, 125I-B2 (2-nitro-4-azidophenylacetyl)-des-PheB1-insulin, and the pathways in the intracellular processing of the labeled receptors were studied at 37 degrees C. During 37 degrees C incubations, the labeled 440-kDa insulin receptors were continuously internalized (as assessed by trypsin inaccessibility) and degraded such that up to 50% of the initially labeled receptors were lost by 120 min. Metabolic poisons (0.125-0.75 mM 2,4-dinitrophenol (DNP) and 1-10 mM NaF), which led to dose-dependent depletion of adipocyte ATP pools, inhibited receptor loss, and caused up to 3-fold increase in intracellular receptor accumulation. This effect was due to inhibition of intracellular receptor degradation, and there was no apparent effect of the metabolic poisons on initial internalization of the receptors. Following maximal intracellular accumulation of labeled insulin receptors in the presence of NaF or DNP, removal of these agents resulted in a subsequent, time-dependent degradation of the accumulated receptors. However, when the lysosomotropic agent, chloroquine (0.2 mM), was added immediately following removal of the metabolic poisons, further degradation of the intracellularly accumulated receptors was prevented, suggesting that the chloroquine-sensitive degradation of insulin receptors occurs distal to the site of inhibition by NaF or DNP. To confirm this, maximal intracellular accumulation of labeled receptors was first allowed to occur in the presence of chloroquine and the cells were then washed and reincubated in chloroquine-free media in the absence or presence of NaF or DNP. Under these conditions, degradation of the intracellularly accumulated receptors continued to occur, and NaF or DNP failed to block the degradation.

• Research Organization: Univ. of Colorado Health Sciences Center, Denver (USA)
• OSTI ID: 7191926
• Journal Information: J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 263:12; ISSN JBCHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
560300 -- Chemicals Metabolism & Toxicology
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ADIPOSE TISSUE
ANIMAL CELLS
ANIMAL TISSUES
ANIMALS
AROMATICS
ATP
AZIDES
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL EFFECTS
BIOLOGICAL PATHWAYS
BODY
CHEMISTRY
CONNECTIVE TISSUE
CONNECTIVE TISSUE CELLS
DAYS LIVING RADIOISOTOPES
DOSE-RESPONSE RELATIONSHIPS
ELECTRON CAPTURE RADIOISOTOPES
ENZYMES
FAT CELLS
HORMONES
HYDROLASES
HYDROXY COMPOUNDS
INHIBITION
INSULIN
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
MAMMALS
MEMBRANE PROTEINS
MEMBRANE TRANSPORT
METABOLISM
NITRO COMPOUNDS
NITROGEN COMPOUNDS
NITROPHENOL
NUCLEI
NUCLEOTIDES
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PEPTIDE HORMONES
PEPTIDE HYDROLASES
PHENOLS
PHOTOCHEMISTRY
PROTEINS
RADIOISOTOPES
RATS
REACTION KINETICS
RECEPTORS
RODENTS
SERINE PROTEINASES
SOMATIC CELLS
TIME DEPENDENCE
TISSUES
TRACER TECHNIQUES
TRYPSIN
VERTEBRATES