Mediates the positive regulation of the beta-glucoside (arb) operon by functioning as a transcriptional antiterminator. This is an RNA-binding protein that recognizes a specific sequence located just upstream of two termination sites within the operon (By similarity). Phosphorylated and inactivated by ArbF (EII-Bgl). The degree of phosphorylation is dependent on the presence or absence of beta-glucosides which act as inducers of the operon expression. Addition of inducer result in the rapid dephosphorylation of ArbG (By similarity). Belongs to the transcriptional antiterminator BglG family.