This family represents the N-terminus of bacterial ARAC-type transcriptional regulators. In E. coli, these regulate the L-arabinose operon through sensing the presence of arabinose, and when the sugar is present, transmitting this information from the arabinose-binding domains to the protein's DNA-binding domains [1]. This family might represent the N-terminal arm of the protein, which binds to the C-terminal DNA binding domains to hold them in a state where the protein prefers to loop and remain non-activating [2]. All family members contain the Pfam:PF00165 domain.

1: Mutational analysis of residue roles in AraC function. Ross JJ, Gryczynski U, Schleif R; J Mol Biol 2003;328:85-93. PMID:12683999

2: Arm-domain interactions in AraC. Saviola B, Seabold R, Schleif RF; J Mol Biol 1998;278:539-548. PMID:9600837