Furthermore, depletion of NusG has no effect on lambda N antitermination in vivo, and unlike nusA, nusB, and nusE, no point mutations in nusG that block N activity have been isolated. A NusG homolog, RfaH, enhances elongation of several transcripts in E. coli and S. typhimurium. The possibility that RfaH and NusG are redundant for N antitermination has not yet been tested, although for several other functions, the two proteins are not interchangeable.