Characterization of the transferrin receptor in tunicamycin-treated A431 cells.
The transferrin receptor undergoes extensive co- and post-translational modifications during its biosynthesis. In this study, the functional and structural properties of the transferrin receptor from tunicamycin-treated A431 cells were examined. Incubation of A431 cells with this inhibitor of asparagine-linked glycosylation results in a shift of the apparent molecular weight of the transferrin receptor from 94,000 to 79,000. The electrophoretic mobility of the receptor from treated cells is that of a monomer under nonreducing conditions, whereas the transferrin receptor in untreated cells has the mobility of a dimer under identical conditions. This result indicates a lack of disulfide bond formation between subunits of the receptor from tunicamycin-treated cells. In solution no dimers can be detected with cross-linking studies. This unglycosylated receptor does not appear to stably bind transferrin as demonstrated by a lack of isolation of this form of the receptor with transferrin-linked Sepharose. It is not transported to the surface of A431 cells.
Reckhow
C L
CL
Department of Biology, Syracuse University, New York 13244.
Enns
C A
CA
D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D006801:Humans; D008970:Molecular Weight; D011990:Receptors, Transferrin / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D014415:Tunicamycin / Q000494:pharmacology*
D011990:Receptors, Transferrin; D014415:Tunicamycin