The competition between transferrins labeled with 59Fe, 65Zn, and 54Mn for the binding sites on lactating mouse mammary gland cells.
Using a homologous competition of 54Mn-transferrin with Mn-transferrin and 65Zn-transferrin with Zn-transferrin, it was found that on the plasma membrane of lactating mouse mammary gland cells there are receptor binding Mn-transferrin and Zn-transferrin. The heterologous competition between labeled and nonlabeled Fe-transferrin, Mn-transferrin and Zn-transferrin, as well as almost equal affinity constants of cellular receptors toward the three metals by competition of Fe-transferrin suggests that one and the same receptor accepts all three metals from the transferrin molecule. The cell receptors therefore possess a polymetal binding function. A model and a mechanism for regulation of the transport metal flow toward the mammary gland cell acting like "automated switching over" are proposed.
Moutafchiev
D
D
Department of Biochemistry, Medical Faculty, Medical University, Sofia, Bulgaria.
Sirakov
L
L
Bontchev
P
P
D000818:Animals; D001667:Binding, Competitive; D066298:In Vitro Techniques; D007504:Iron Radioisotopes; D007774:Lactation; D008321:Mammary Glands, Animal / Q000378:metabolism* / Q000502:physiology; D008345:Manganese; D051379:Mice; D011869:Radioligand Assay; D014168:Transferrin / Q000378:metabolism*; D015037:Zinc Radioisotopes
D007504:Iron Radioisotopes; D014168:Transferrin; D015037:Zinc Radioisotopes; D008345:Manganese