On the nature of permeability of sarcoma-180 cells to amethopterin in vitro.

  title={On the nature of permeability of sarcoma-180 cells to amethopterin in vitro.},
  author={Maire T. Hakala},
  journal={Biochimica et biophysica acta},
  volume={102 1},
  • M. Hakala
  • Published 25 May 1965
  • Biology
  • Biochimica et biophysica acta

On the nature of a transport alteration determining resistance to amethopterin in the L1210 leukemia.

Kinetic analysis revealed an increase in the Michaelis constant for the system in these resistant cells, suggesting an alteration in the binding properties of a carrier component as the basis for the impairment.

Differential cell permeability and the basis for selective activity of methotrexate during therapy of the L1210 leukemia.

A far greater persistence of free MTX and a more sustained metabolic effect in L1210 cells than in small intestine is revealed, at least in part, to a more effective influx of drug in L 1210 cells at low plasma levels.

Stereochemical characteristics of the folate-antifolate transport mechanism in L1210 Leukemia cells.

The relationship between the values for initial velocity of influx (v), the Km and Vmax obtained with each analog are in agreement with that predicted by the Michaelis-Menten equation and is consistent with the notion that differences in rates of influx are attributable to differences in the affinity of the carrier for the system.

Genetically Alterable Transport of Amethopterin in Diplococcus pneumoniae I. Physiological Properties and Kinetics of the Wild-type System

A system of H3-amethopterin uptake, physiologically and kinetically resembling active transport, has been described in Diplococcus pneumoniae. Uptake by this system has a pH optimum near 6.0, is

Effects of 2,4-dinitrophenol and other metabolic inhibitors on the bidirectional carrier fluxes, net transport, and intracellular binding of methotrexate in Ehrlich ascites tumor cells.

Although most metabolic inhibitors affect MTX transport by inhibition of energy metabolism, DNP affects the system in at least two ways: (a) by energy depletion similar to that of other metabolic inhibitors; and (£>) by an apparent interaction with the carrier at the cell membrane which inhibits bidirectional fluxes.



Azaserine resistance in a plasma-cell neoplasm without change in active transport of the inhibitor.

It is concluded that a difference in transport capacity cannot explain the biological resistance of the 70429/Az(la) line nor account for the differences previously observed with intact cells in azaserine inhibition of purine biosynthesis.


The 2-methyl-4-amino-5-hydroxymethylpyrimidine form of the thiamine pyrimidine has been examined for its effect on the entry of aminopterin-2-C04 into B. subtilis.

Chromosomal constitution and amethopterin resistance in cultured mouse cells.

Extensive selection is shown to be involved in the development of the amethopterin-resistant cell lines, most probably based on the capacity of a cell to rapidly increase the content of folic acid reductase.

Active transport of O-diazoacetyl-L-serine and 6-diazo-5-oxo-L-norleucine in Ehrlich ascites carcinoma.

The intracellular-extracellular concentration gradient attained in this concentration process is greater than that reported for all the “normal” amino acids.

The metabolism of tritiated folic acid in man.

Tritiated folic acid has been prepared and some aspects of its metabolism in man studied by nonmicrobiological assay methods, and the present paper presents the results of these studies.