Associates with the boxA element in its own promoter (PubMed:29229908). Part of the processive rRNA transcription and antitermination complex (rrnTAC). The complex forms an RNA-chaperone ring around the RNA exit tunnel of RNA polymerase (RNAP). It supports rapid transcription and antitermination of rRNA operons, cotranscriptional rRNA folding, and annealing of distal rRNA regions to allow correct ribosome biogenesis. This subunit may play a central role in organizing the structure (By similarity). a myo-inositol phosphate + H2O = myo-inositol + phosphate Homodimer. The rRNA transcription and antitermination complex (rrnTAC) consists of RNA polymerase (RNAP), NusA, NusB, NusE (rpsJ), NusG, SubB, ribosomal protein S4, DNA and precursor rRNA; S4 is more flexible than other subunits. Repressed by the Nus factor complex (NusA, NusB, NusE (rpsJ), NusG and SuhB). Belongs to the inositol monophosphatase superfamily.