gamma-L-glutamyl-L-glutamyl-[tubulin] + ADP + phosphate + H(+) => L-glutamyl-[tubulin] + L-glutamate + ATP
gamma-l-glutamyl-l-glutamyl-[tubulin] + adp + phosphate + h(+) => l-glutamyl-[tubulin] + l-glutamate + atp