Transfer of copper from metallothionein to nonmetallothionein proteins in cultured cells |
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Authors: | JeanClare Seagrave John L Hanners Wayne Taylor Harold A O'Brien |
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Institution: | (1) Genetics Group, LS-3, Los Alamos National Laboratory, MS M886, 87545 Los Alamos, NM;(2) Medical Radioisotope Research Group, INC-3, MS J514, 87545 Los Alamos, NM;(3) Present address: Department Cell Pathology, Univ. New Mex. School of Medicine, Surge Bldg., 87131 Albuquerque, New Mexico |
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Abstract: | Copper uptake and distribution with time among cytoplasmic proteins were followed in cultured cells under several conditions:
(1) CHO cells, which cannot synthesize metallothioneins, were labeled with67Cu in the presence of 100 μM ZnCl2; (2) Cdr30F9 cells, which contain some constitutive metallothionein (MT), were labeled in the absence of additional ZnCl2 and; (3) Cdr30F9 cells were labeled in the presence of ZnCl2, under which conditions they synthesized additional metallothioneins. The exogenous67Cu and ZnCl2, where present, were then removed, and the distributions of67Cu among size fractions of the cellular proteins were observed at intervals for 16 h. In addition, a culture identical to
condition (3) above was also treated with 100 μM ZnCl2 during the redistribution period. The67Cu was initially resolved into three peaks by Sephadex G-75 chromatography: high molecular weight, intermediate molecular
weight, and MT. The67Cu in the MT fraction decreased with at
1/2 of 10–12 h. In contrast to this, generally, in cells with a higher initial67Cu bound to metallothionein, there was a progressive increase in the amount of67Cu eluting with the high- and intermediate-molecular-weight fractions. Since no other source of67Cu was available, these experiments suggest that copper stored in MT can be transferred to other proteins in these cells. |
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Keywords: | Metallothionein transfer of copper from copperthionein physiological copper reservoir copper transfer copper in cultured cells CHO cells cadmium-resistant CHO cell variants |
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