This RNA binding domain is found at the amino terminus of transcriptional antitermination proteins such as BglG, SacY and LicT. These proteins control the expression of sugar metabolising operons in Gram+ and Gram- bacteria. This domain has been called the CAT (Co-AntiTerminator) domain. It binds as a dimer to short Ribonucleotidic Anti-Terminator (RAT) hairpin, each monomer interacting symmetrically with both strands of the RAT hairpin. In the full-length protein, CAT is followed by two phosphorylatable PTS regulation domains (pfam00874) that modulate the RNA binding activity of CAT. Upon activation, the dimeric proteins bind to RAT targets in the nascent mRNA, thereby preventing abortive dissociation of the RNA polymerase from the DNA template.