preferred_name: serotonin(in) + 2 H(+)(out) => serotonin(out) + 2 H(+)(in)
preferred_name_lc: serotonin(in) + 2 h(+)(out) => serotonin(out) + 2 h(+)(in)
label: serotonin(in) + 2 H(+)(out) => serotonin(out) + 2 H(+)(in)
label_lc: serotonin(in) + 2 h(+)(out) => serotonin(out) + 2 h(+)(in)