Identification of Insulin-Degrading Enzyme on the Surface of Cultured Human Lymphocytes, Rat Hepatoma Cells, and Primary Cultures of Rat Hepatocytes*

Endocrinology ◽  
1982 ◽  
Vol 111 (4) ◽  
pp. 1102-1108 ◽  
Author(s):  
KOICHI YOKONO ◽  
RICHARD A. ROTH ◽  
SHIGEAKI BABA
Keyword(s):  
Human Lymphocytes ◽  
Primary Cultures ◽  
Rat Hepatocytes ◽  
Hepatoma Cells ◽  
Insulin Degrading Enzyme ◽  
Degrading Enzyme ◽  
Rat Hepatoma ◽  
Rat Hepatoma Cells

scholarly journals Membrane potential of rat hepatoma cells in culture: Influence of factors affecting amino acid transport

1995 ◽  
Vol 15 (4) ◽  
pp. 173-184 ◽  
Author(s):  
M. F. Mouat ◽  
A. C. Cantrell ◽  
K. L. Manchester
Keyword(s):  
Membrane Potential ◽  
Amino Acid ◽  
Amino Acid Transport ◽  
Rat Hepatocytes ◽  
Hepatoma Cells ◽  
Acid Transport ◽  
Factors Affecting ◽  
Cells In Culture ◽  
Rat Hepatoma ◽  
Rat Hepatoma Cells

The effect has been studied of various media, hormones and of amino acids on the membrane potential of rat hepatoma cells in culture measured by microelectrode impalement. Cells in Eagle's minimal essential medium plus 5% serum had a value which varied daily from about 5–8 mV, inside negative. The membrane potential of rat hepatocytes was measured to be 8.7 ± 0.2mV, inside negative. The membrane potential of the hepatoma cells was decreased by insulin and increased by glucagon. Membrane potential was unaffected by change of medium to Hanks' or Earle's balanced salt solutions or deprivation of serum. It was, however, reduced in cells in phosphate-buffered saline and by reduction of pH. The former effect was shown to be due to the higher [Na+] of phosphat-buffered saline as opposed to the other media. Addition of alanine, glycine, serine, proline and methylaminoisobutyrate all reduced membrane potential by 2–3 mV. Smaller decreases were seen with methionine, leucine and phenylalanine, but none with glutamine, threonine, BCH (2-aminonorborane-2-carboxylic acid) and D-alanine. The results are compared with the effects of similar conditions on aminoisobutyrate uptake. Whilst there was a correlation under some conditions there was not under others. It is concluded that for the hepatoma cells factors additional to the membrane potential must exert some influence on the capacity for amino acid transport.

scholarly journals Rat hepatoma cells express novel transport systems for glutamine and glutamate in addition to those present in normal rat hepatocytes

1998 ◽  
Vol 330 (1) ◽  
pp. 255-260 ◽  
Author(s):  
D. John MGIVAN
Keyword(s):  
Cell Line ◽  
Transport System ◽  
Hepatoma Cell ◽  
Rat Hepatocytes ◽  
Hepatoma Cells ◽  
Transport Systems ◽  
Hepatoma Cell Line ◽  
High Affinity ◽  
Rat Hepatoma ◽  
Rat Hepatoma Cells

The rat hepatoma cell line H4-II-E was found to express much higher activities of Na+-dependent glutamine and aspartate transport than those observed in normal cultured hepatocytes, in agreement with previous work of others on human hepatocytes. Na+-dependent glutamine transport in rat hepatoma cells could be resolved into two components. One was pH-dependent, tolerated Li+ for Na+ substitution and was inhibited only by asparagine and histidine; characteristics similar to those of transport System N in hepatocytes. The other transport system had a similar Km for glutamine but was pH independent, did not accept Li+ ions and was completely inhibited by excess concentrations of lysine, histidine, leucine, serine and cysteine, but not by methyl-aminoisobutyrate or phenylalanine. This pattern of inhibition is distinct from that of any transporter occurring in normal hepatocytes and may indicate the presence of a new transporter isoform. Similar results were obtained with the cell line HTC. Na+-dependent aspartate transport in H4 hepatoma cells was mediated by a high-affinity system (Km 5 μM) and was inhibited by D-aspartate and L-glutamate but not by D-glutamate - properties characteristic of the high-affinity glutamate transporter EAAC1. C-terminal antibodies to the EAAC1 protein recognized a single band of 58 kDa in hepatocyte membranes, but an additional strong band of 60 kDa was present in H4 hepatoma cells. These results provide further evidence for the view that tumour cells may express additional isoforms of amino acid transport systems which are not present in non-transformed cells.

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