Proteins of the iniBAC operon all give rise to multidrug resistance when mutated.  They may function with the MFS drug efflux pump, EfpA (TC# 2.A.1.3.78).  See family description for the evidence that ImiABC is involved in drug resistance (Colangeli et al. 2007). ImiA and ImiC have N-terminal regions that are homologous to each other. IniB is rich in glycines and shows apparent similarity to members of families 9.B.96, 1.B.89, 1.B.94 and 1.B.95, all of which may belong to the PE/PPE superfamily and are glycine-rich.  The apparent similarity may be an artifactual due the presence of redundant sequences of similar limited amino acid compositions.