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Transferrin receptor numbers and transferrin and iron uptake in cultured chick muscle cells at different stages of development
Author(s) -
Sorokin L. M.,
Morgan E. H.,
Yeoh G. C. T.
Publication year - 1987
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041310306
Subject(s) - transferrin , transferrin receptor , endocytosis , receptor , myogenesis , biology , myocyte , dna synthesis , microbiology and biotechnology , biochemistry , medicine , dna
The mechanism of iron uptake and the changes which occur during cellular development of muscle cells were investigated using primary cultures of chick embryo breast muscle. Replicating presumptive myoblasts were examined in exponential growth and after growth had plateaued. These were compared to the terminally differentiated cell type, the myotube. All cells, regardless of the state of growth or differentiation, had specific receptors for transferrin. Presumptive myoblasts in exponential growth had more transferrin receptors (3.78 ± 0.24 × 10 10 receptors/μg DNA) than when division had ceased (1.70 ± 0.14 × 10 10 receptors/μg DNA), while myotubes had 3.80 ± 0.26 × 10 10 receptors/μg DNA. Iron uptake occurred by receptor‐mediated endocytosis of transferrin. While iron was accumulated by the cells, apotransferrin was released in an undegraded form. There was a close correlation between the molar rates of endocytosis of transferrin and iron. Maximum rates of iron uptake were significantly higher in myotubes than in presumptive myoblasts in either exponential growth or after growth had plateaued. There were two rates of exocytosis of transferrin, implying the existence of two intracellular pathways for transferrin. These experiments demonstrate that iron uptake by muscle cells in culture occurs by receptor‐mediated endocytosis of transferrin and that transferrin receptor numbers and the kinetics of transferrin and iron uptake vary with development of the cells.