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