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Transferrin—Reticulocyte Binding: Evidence for the Functional Importance of Transferrin Conformation
Author(s) -
Lane R. S.
Publication year - 1972
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/j.1365-2141.1972.tb05677.x
Subject(s) - transferrin , reticulocyte , transferrin receptor , biochemistry , chemistry , biology , microbiology and biotechnology , gene , messenger rna
S ummary Iron‐free and 59 Fe‐labelled human and rabbit 125 I‐transferrins have been chromatographed on DEAE cellulose at pH 7.9 and have also been incubated with rabbit reticulocytes in order to determine transferrin and iron uptake. Chromatography of human apo‐ and iron‐transferrin indicated clear differences in their surface properties which are considered to be conformation‐dependent. These differences were not evident in rabbit transferrin samples. Human and rabbit iron‐transferrins and rabbit apo‐transferrin all associated rapidly with rabbit reticulocytes; human apo‐transferrin was only weakly bound. Correlation of data from both experiments suggested that reticulocyte binding of human apo‐transferrin is limited by its molecular confirmation. The incubation studies confirmed results of other workers and indicated that the data from these experiments with human and rabbit transferrin are not in conflict. Compared with rabbit iron‐transferrin, only half as much human iron‐transferrin was bound to rabbit reticulocytes in a comparable experiment. Iron transfer from bound human and rabbit transferrin took place at equal rate. It is argued that fewer receptors on rabbit reticulocytes are available for human transferrin because, when bound, the size and shape of a molecule limits further binding of transferrin molecules at adjacent sites.