when compensation was made for transport differences between these compounds by adjusting the extracellular drug concentrations to achieve equivalent intracellular monoglutamyl substrate levels , the polyglutamylation of aminopterin was still 2.8-fold greater than that for methotrexate , suggesting that aminopterin is a better substrate for the folylpolyglutamate synthetase as well as the transport carrier .
C0025677
methotrexate
C0002583
aminopterin