preferred_name: Na(+)(out) + NH4(+)(in) => Na(+)(in) + NH4(+)(out)
preferred_name_lc: na(+)(out) + nh4(+)(in) => na(+)(in) + nh4(+)(out)
label: Na(+)(out) + NH4(+)(in) => Na(+)(in) + NH4(+)(out)
label_lc: na(+)(out) + nh4(+)(in) => na(+)(in) + nh4(+)(out)