This paper is devoted to investigation of the interaction of a protein from the EB family (End Binding protein) with microtubules (MT) in vitro . According to one of the hypotheses, it has an enhanced affinity for the «tubulin-GDF-phosphate» complex, suggesting that the addition of inorganic phosphate to solution should increase the affinity of EB1 to MT. To test this assumption, we conducted experiments to observe the kinetics of accumulation of recombinant EB1-eGFP protein on stable MTs using TIRF microscopy (Total Internal Reflection Fluorescence) in the presence of taxol, which suppresses the depolymerization of MT. Moreover, the dynamic MT parameters and the size of the binding region of EB1-eGFP with dynamic MTs were measured. Comparing these data obtained at different concentrations of sodium dihydrogen phosphate in solution, one can draw conclusions about the effect of phosphate on the affinity of EB1 to MT, and therefore on the mechanism of their interaction. The results of this study evidence against the hypothesis that EB1 binds to GDF-phosphate-tubulin
1, MAPs, microtubules, GTP-cap
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