a gentamycin + GTP <=> a gentamycin 2''-phosphate + GDP + H(+)
a gentamycin + gtp <=> a gentamycin 2''-phosphate + gdp + h(+)
a gentamycin + GTP <=> a gentamycin 2''-phosphate + GDP + H(+)
a gentamycin + gtp <=> a gentamycin 2''-phosphate + gdp + h(+)