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Evaluation of Mg 2+ as an intracellular regulator of uridine uptake
Author(s) -
Vidair C.,
Rubin H.
Publication year - 1981
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.1041080305
Subject(s) - uridine , intracellular , stimulation , biophysics , nucleoside , biochemistry , uridine triphosphate , chemistry , enzyme , regulator , thymidine , microbiology and biotechnology , biology , rna , nucleotide , in vitro , endocrinology , gene
The rate of uptake of the nucleoside uridine increases within minutes after adding a growth stimulus to quiescent 3T3 cells. We have previously shown this uptake rate to be highly sensitive to changes in the intracellular concentration of Mg 2+ . In the present paper, the alteration of uptake by Mg 2+ is shown to occur at the phosphorylation step — the same point at which serum acts to modulate uridine uptake. The serum stimulation of uridine uptake can be mimicked by Mg 2+ alone or blocked by partially depleting cells of their Mg 2+ . Work with cell‐free extracts shows that the uridine kinase enzyme responds to Mg 2+ in a manner similar to that exhibited by whole cells whose concentrations of Mg 2+ have been raised. In addition, the enzyme's inhibition by ATP is relieved by raising the Mg 2+ concentration. Thymidine uptake, a reaction which does not respond quickly to mitogenic stimulation, is unaffected by alterations in Mg 2+ concentration. These results are discussed in terms of a possible role for Mg 2+ as an intracellular regulator of uridine uptake and other reactions of the coordinate response of cells to external effectors.