Source:http://linkedlifedata.com/resource/umls/id/C1153616
GO: Catalysis of 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. [ISBN:0198506732]