citrate(in) + H(+)(in) => citrate(out) + H(+)(out)
citrate(in) + h(+)(in) => citrate(out) + h(+)(out)
citrate(in) + H(+)(in) => citrate(out) + H(+)(out)
citrate(in) + h(+)(in) => citrate(out) + h(+)(out)