Receptor-mediated endocytosis of the intrinsic factor-cobalamin complex in HT 29, a human colon carcinoma cell line.
A HT 29 cell line derived from human colonic carcinoma was shown to express the intrinsic factor receptor, with about 5000 binding sites per cell and an association constant of 20 x 10(9) 1/mol at pH 7.4 and 4 degrees C. The number of binding sites increased dramatically between 7 and 10 days of culture time. Endocytosis of the intrinsic factor-cobalamin-receptor complex was inhibited by two ways: at 4 degrees C and at 37 degrees C by incubating the cells with vinblastine, monensin and chloroquine. The plasma membrane receptor was cross-linked to [57Co]cobalamin-intrinsic factor and solubilized with Triton X-100. The cross-linked complex had a relative molecular mass of 330 kDa in native PAGE.
Guéant
J L
JL
Laboratoire de Biochimie Médicale, U 308 INSERM, Faculté de Médecine, Vandoeuvre-lés-Nancy, France.
Masson
C
C
Schohn
H
H
Girr
M
M
Saunier
M
M
Nicolas
J P
JP
D002738:Chloroquine / Q000494:pharmacology; D002850:Chromatography, Gel; D003110:Colonic Neoplasms; D004591:Electrophoresis, Polyacrylamide Gel; D004705:Endocytosis; D006801:Humans; D007437:Intrinsic Factor / Q000378:metabolism*; D007700:Kinetics; D011956:Receptors, Cell Surface / Q000378:metabolism; D014407:Tumor Cells, Cultured; D014805:Vitamin B 12 / Q000378:metabolism*
D011956:Receptors, Cell Surface; D002738:Chloroquine; D007437:Intrinsic Factor; D014805:Vitamin B 12