Formation of vesicular copper by K562 plasma membranes: A possible role in cellular copper uptake and transport

Conference · Fri Mar 15 04:00:00 EST 1991 · FASEB Journal (Federation of American Societies for Experimental Biology); (United States)

OSTI ID:5239337

Davidson, L A; McOrmond, S L; Harris, E D ^[1]

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1. Texas A and M Univ., College Station (United States)

Copper from ceruloplasmin (Cp) is taken up by K562 cells independently of Cp and incorporated into superoxide dismutase. The process of release from Cp, transport across the plasma membrane and into the enzyme target is unclear. The authors now have evidence that copper from Cp may be converted into a vesicular form during the uptake process. After incubating {sup 67}CuCp with K562 plasma membranes, the resultant supernatant was applied to a discontinuous sucrose gradient. {sup 67}Cu peaks appeared at each interface and were subjected to Percoll gradient fractionation. The fraction from the heaviest sucrose interface resulted in a distinct peak on Percoll gradients, showing a component with a buoyant density of 1.042. K562 cells have been shown to produce two populations of endosomes of densities 1.04 and 1.06. This isolated vesicular copper is capable of donating {sup 67}Cu to intact cells and this donation is inhibited by N-ethyl maleimide (NEM), a sulfhydryl reagent which also significantly decreases Cp-copper uptake by intact cells. However, NEM does not affect incorporation of {sup 67}Cu into vesicles. In whole cell studies, {sup 67}Cu from Cp co-migrates with {sup 125}I-transferrin in Percoll gradients, an indication that {sup 67}Cu is being transported into the cell via an endosome, which has been shown to occur for transferrin.

• OSTI ID: 5239337
• Report Number(s): CONF-9104107--
• Conference Information: Journal Name: FASEB Journal (Federation of American Societies for Experimental Biology); (United States) Journal Volume: 5:5
• Country of Publication: United States
• Language: English

Related Subjects

560300* -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL MATERIALS
BLOOD
BLOOD PLASMA
BODY FLUIDS
CELL CONSTITUENTS
CELL MEMBRANES
CERULOPLASMIN
COMPLEXES
COPPER
COPPER 67
COPPER COMPLEXES
COPPER ISOTOPES
DAYS LIVING RADIOISOTOPES
ELEMENTS
ENZYMES
FRACTIONATION
GLOBULINS
GLOBULINS-ALPHA
INTERMEDIATE MASS NUCLEI
ISOTOPE APPLICATIONS
ISOTOPES
MATERIALS
MEMBRANE TRANSPORT
MEMBRANES
METABOLISM
METALLOPROTEINS
METALS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
OXIDOREDUCTASES
PROTEINS
RADIOISOTOPES
REAGENTS
SEPARATION PROCESSES
SUPEROXIDE DISMUTASE
TRACER TECHNIQUES
TRANSITION ELEMENT COMPLEXES
TRANSITION ELEMENTS
UPTAKE