Abstract
A model is presented for the interference of GTP hydrolysis in the mechanism of microtubule assembly. This model is suggested by previous results showing that both GTP and GDP are present at microtubule ends because of GTP hydrolysis and that tubulin does not bind to a GDP-bound end. The analytical theory developed here is aimed at calculation of the steady-state subunit flux at one end of the polymer. The GTP/GDP features just mentioned result in a nonlinear plot of the flux vs. tubulin concentration. Microtubules are predicted to exhibit a differen kinetic behavior below and avove the critical concentration, which can be considered as a transition between 2 regimes.