2 GDP + 2 H(+) => P(1),P(4)-bis(5'-guanosyl) tetraphosphate + H2O
2 gdp + 2 h(+) => p(1),p(4)-bis(5'-guanosyl) tetraphosphate + h2o
2 GDP + 2 H(+) => P(1),P(4)-bis(5'-guanosyl) tetraphosphate + H2O
2 gdp + 2 h(+) => p(1),p(4)-bis(5'-guanosyl) tetraphosphate + h2o