part of part of has primary input quaternary nitrogen compound quaternary ammonium group transmembrane transporter activity quaternary ammonium compound transporter activity GO:0015202 Enables the transfer of quaternary ammonium groups from one side of a membrane to the other. Quaternary ammonium groups are any compound that can be regarded as derived from ammonium hydroxide or an ammonium salt by replacement of all four hydrogen atoms of the NH4+ ion by organic groups. GO:0015651 quaternary amine transmembrane transporter activity quaternary ammonium group transport transmembrane transporter activity