Effects of lithium ions on actin polymerization in the presence of magnesium ions.
In spite of the abundant literature, questions on the biological action of Li+ are far from being answered. In the present paper we demonstrate that modification of the salt composition of the medium for actin polymerization, by gradually replacing K+ with Li+, leads to a dose-related change in the time course of actin assembly. The presence of Li+ influences actin polymerization in vitro by enhancing nucleation and decreasing critical monomer concentration at steady state. Furthermore, Li+ stabilizes actin polymers mainly by lowering the absolute value of the dissociation rate constant (K-) and shifting (towards lower values of actin monomer concentrations) the range of G-actin concentrations in which filament-subunit flux can occur. The influence of Li+ on actin and tubulin polymerization in vitro suggests that cytoskeletal structures could be some of the cytoplasmic targets of this ion.
Colombo
R
R
Department of Biology, University of Milan, Italy.
Milzani
A
A
Contini
P
P
Dalle Donne
I
I
D000199:Actins / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D002712:Chlorides / Q000494:pharmacology*; D003432:Cross-Linking Reagents / Q000494:pharmacology; D007700:Kinetics; D008094:Lithium / Q000494:pharmacology*; D018021:Lithium Chloride; D046911:Macromolecular Substances; D008274:Magnesium / Q000494:pharmacology*; D008301:Maleimides / Q000494:pharmacology; D009132:Muscles / Q000378:metabolism; D011817:Rabbits; D013050:Spectrometry, Fluorescence / Q000379:methods
D000199:Actins; D002712:Chlorides; D003432:Cross-Linking Reagents; D046911:Macromolecular Substances; D008301:Maleimides; D008094:Lithium; C011328:N,N'-4-phenylenedimaleimide; D018021:Lithium Chloride; D008274:Magnesium