scholarly journals The properties and extracellular location of 5′-nucleotidase of the rat fat-cell plasma membrane

1975 ◽  
Vol 146 (3) ◽  
pp. 625-633 ◽  
Author(s):  
A C Newby ◽  
J P Luzio ◽  
C N Hales
Keyword(s):  
Plasma Membrane ◽  
Fat Cells ◽  
Isolated Fat Cells ◽  
Fat Cell ◽  
Cell Plasma Membrane ◽  
Intact Cells ◽  
Low Concentrations ◽  
Cell Plasma ◽  
Atp Analogues ◽  
Extracellular Location

1. A phosphohydrolase specific for 5′-nucleotides was characterized by using a particulate fraction from isolated fat-cells. 2. The activity of intact cells towards 5′-AMP was studied. 3. The activity in either situation had the same KM for AMP (45 muM) and was inhibited by low concentrations of ATP (less than 50 muM), but less potently by the ATP analogues AMP-P(CH2)P(adenylyl (β γ-methylene)diphosphonate) and AMP-P)NH)P (adenylylimidodiphosphate). 4. Homogenization of intact fat-cells caused no increase in activity and at least 85% of the activity was recovered in the particulate preparation. 5. The preparation of fat-cells used in this work was not freely permeable to AMP. 6. The ability of intact fat-cells to hydrolyse AMP implies that 5′-nucleotidase is an ectoenzyme in fat-cells. 7. Concentrations of ATP 100 times lower than intracellular concentrations inhibit the enzyme when added extracellularly to intact fat-cells, implying that this effect is also medicated at the extracellular face of the membrane. 8. Antibodies raised to whole liver cells and whole fat-cells inhibit 5′-nucleotidase in intact cells. 9. Incubation of intact fat-cells with adrenaline (1 mug/ml) or insulin (50 mui.u./ml) failed to alter the KM or Vmax. of the enzyme.

scholarly journals A rapid immunological procedure for the isolation of hormonally sensitive rat fat-cell plasma membrane

1976 ◽  
Vol 154 (1) ◽  
pp. 11-21 ◽  
Author(s):  
J P Luzio ◽  
A C Newby ◽  
C N Hales
Keyword(s):  
Plasma Membrane ◽  
Adenylate Cyclase ◽  
Plasma Membranes ◽  
Membrane Preparation ◽  
Fat Cells ◽  
Fat Cell ◽  
Cell Plasma ◽  
Rat Fat Cells ◽  
Plasma Membrane Preparation ◽  
Isolated Rat

1. A rapid method for the isolation of hormonally sensitive rat fat-cell plasma membranes was developed by using immunological techniques. 2. Rabbit anti-(rat erythrocyte) sera were raised and shown to cross-react with isolated rat fat-cells. 3. Isolated rat fat-cells were coated with rabbit anti-(rat erythrocyte) antibodies, homogenized and the homogenate made to react with an immunoadsorbent prepared by covalently coupling donkey anti-(rabbit globulin) antibodies to aminocellulose. Uptake of plasma membrane on to the immunoadsorbent was monitored by assaying the enzymes adenylate cyclase and 5′-nucleotidase and an immunological marker consisting of a 125I-labelled anti-(immunoglobulin G)-anti-cell antibody complex bound to the cells before fractionation. Contamination of the plasma-membrane preparation by other subcellular fractions was also investigated. 4. By using this technique, a method was developed allowing 25-40% recovery of plasma membrane from fat-cell homogenates within 30 min of homogenization. 5. Adenylate cyclase in the isolated plasma-membrane preparation was stimulated by 5 μm-adrenaline.

PROTEIN KINASE ACTIVITY ASSOCIATED WITH THE FAT CELL PLASMA MEMBRANE

1981 ◽  
Vol 9 (2) ◽  
pp. 232P-232P
Author(s):  
G. J. Belsham ◽  
R. W. Brownsey ◽  
R. M. Denton
Keyword(s):  
Plasma Membrane ◽  
Protein Kinase ◽  
Kinase Activity ◽  
Protein Kinase Activity ◽  
Fat Cell ◽  
Cell Plasma Membrane ◽  
Cell Plasma

Thiol-Dependent Subunit Interactions of a Major Fat Cell Plasma Membrane Glycoprotein

1978 ◽  
Vol 2 (1) ◽  
pp. 97-115 ◽  
Author(s):  
Carlene A. Hawksley ◽  
Nancy Z. Guggenheim ◽  
Michael P. Czech
Keyword(s):  
Plasma Membrane ◽  
Membrane Glycoprotein ◽  
Fat Cell ◽  
Subunit Interactions ◽  
Cell Plasma Membrane ◽  
Cell Plasma

scholarly journals Selective extraction of an intrinsic fat-cell plasma-membrane glycoprotein by Triton X-100

FEBS Letters ◽  
1977 ◽  
Vol 83 (1) ◽  
pp. 71-75 ◽  
Author(s):  
Carla J. Greenbaum ◽  
Michael F. Shanahan ◽  
Dennis J. Pillion ◽  
Michael P. Czech
Keyword(s):  
Plasma Membrane ◽  
Selective Extraction ◽  
Membrane Glycoprotein ◽  
Fat Cell ◽  
Cell Plasma Membrane ◽  
Cell Plasma ◽  
Triton X

scholarly journals The effect of insulin on plasma-membrane and mitochondrial-membrane potentials in isolated fat-cells

1981 ◽  
Vol 196 (1) ◽  
pp. 133-147 ◽  
Author(s):  
R J Davis ◽  
M D Brand ◽  
B R Martin
Keyword(s):  
Plasma Membrane ◽  
Mitochondrial Membrane ◽  
Weak Acid ◽  
Membrane Potentials ◽  
Ph Gradient ◽  
Protonmotive Force ◽  
Fat Cells ◽  
Fat Cell ◽  
Intact Cells ◽  
Insulin Effect

1. A recently developed technique for the measurement of plasma-membrane and mitochondrial-membrane potentials in intact cells by using the distribution of 86Rb+ and [3H]methyltriphenylphosphonium+ has enabled us to characterize a novel insulin effect on fat-cell mitochondria. For control cells the plasma-membrane and mitochondrial-membrane potentials were 75 mV and 152 mV respectively. Insulin (10 mu units/ml) caused a 9 mV hyperpolarization of the plasma membrane and a 19 mV depolarization of the mitochondrial membrane. 2. The insulin-dependent mitochondrial depolarization was observed at physiological insulin concentrations (10 mu units/ml) and was apparent when the cells metabolized a wide variety of substrates. 3. Evidence from the uptake of the weak acid 5,5-dimethyloxazolidine-2,4-dione by fat-cells was interpreted as indicating that the mitochondrial pH gradient was increased by insulin. 4. Insulin alters the balance between the electrical and pH-gradient components that form the mitochondrial protonmotive force. A model is proposed.

Topography of the fat cell plasma membrane

Biochemistry ◽  
1973 ◽  
Vol 12 (19) ◽  
pp. 3597-3601 ◽  
Author(s):  
Michael P. Czech ◽  
William S. Lynn
Keyword(s):  
Plasma Membrane ◽  
Fat Cell ◽  
Cell Plasma Membrane ◽  
Cell Plasma

scholarly journals Insulin-like actions of nickel and other transition-metal ions in rat fat-cells

1976 ◽  
Vol 154 (2) ◽  
pp. 349-357 ◽  
Author(s):  
E. D Saggerson ◽  
S R. Sooranna ◽  
C J. Evans
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Glucose Utilization ◽  
Transition Metal Ions ◽  
Fat Cells ◽  
Fat Cell ◽  
Cell Plasma Membrane ◽  
Cell Plasma ◽  
Glucose Incorporation ◽  
Rat Fat Cells

NiCl2 (1-6mM) decreased adrenaline and glucagon-stimulated lipolysis in rat fat-cells, and also considerably stimulated [U-14C]glucose incorporation into fat-cell lipids. 2. These insulin-like effects were also observed with CuCl, CuCl2, CoCl2 and (to a lesser extent) with MnCl2. 3. NiCl2 was less effective in mimicking insulin effects on [U-14C]fructose metabolism than on glucose utilization. 4. It is tentatively suggested that these transition-metal ions may mimic actions of insulin at the fat-cell plasma membrane which decrease lipolysis and stimulate glucose transport, but do not mimic certain other effects of the hormone on intracellular metabolic processes. 5. These results are discussed with reference to suggestions that redistributions of cellular Ca2+ are associated with insulin action in fat-cells.

Impairment of insulin binding to the fat cell plasma membrane in the obese hyperglycemic mouse

FEBS Letters ◽  
1972 ◽  
Vol 25 (2) ◽  
pp. 339-342 ◽  
Author(s):  
Pierre Freychet ◽  
Marie Hélène Laudat ◽  
Philippe Laudat ◽  
Gabriel Rosselin ◽  
C.Ronald Kahn ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Insulin Binding ◽  
Fat Cell ◽  
Cell Plasma Membrane ◽  
Cell Plasma
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