Two pathways of transferrin recycling evident in a variant of mouse LMTK- cells.
We describe here the properties of a variant cell line, termed AF192, selected by exposing mouse LMTK- cells to a cytotoxic form of transferrin prepared by conjugating transferrin to diphtheria toxin. AF192 cells were mildly resistant to the transferrin-diphtheria toxin conjugate and were cross-resistant to the protein toxins modeccin, abrin, ricin, and Pseudomonas aeruginosa exotoxin A. AF192 cells had an aberrant transferrin cycle characterized by an approximately 50% reduction in the rate of iron uptake from diferric transferrin, an approximately 25% reduction in the number of surface transferrin receptors, and a time course for transferrin recycling that resolved into two apparent first-order rate processes. The aberrant transferrin cycle was not the result of a failure of endocytosed transferrin to discharge iron; rather, part, but not all, of the transferrin taken up by AF192 cells was diverted to an intracellular site from which it was recycled very slowly.
O'Keefe
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Biology Programs, University of Texas at Dallas, Richardson 75083-0688.
Draper
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D000165:Acridine Orange; D000818:Animals; D002460:Cell Line; D002499:Centrifugation, Density Gradient; D004167:Diphtheria Toxin / Q000494:pharmacology; D004351:Drug Resistance; D004591:Electrophoresis, Polyacrylamide Gel; D007457:Iodine Radioisotopes; D007501:Iron / Q000378:metabolism; D007504:Iron Radioisotopes; D007553:Isotope Labeling; D007700:Kinetics; D051379:Mice; D009154:Mutation; D011990:Receptors, Transferrin / Q000378:metabolism; D014118:Toxins, Biological / Q000494:pharmacology; D014168:Transferrin / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D014508:Urea
D004167:Diphtheria Toxin; D007457:Iodine Radioisotopes; D007504:Iron Radioisotopes; D011990:Receptors, Transferrin; D014118:Toxins, Biological; D014168:Transferrin; C044179:transferrin-diphtheria toxin conjugate; D014508:Urea; D007501:Iron; D000165:Acridine Orange