The many bacterial transcription regulation proteins which bind DNA through a 'helix-turn-helix' motif can be classified into subfamilies on the basis of sequence similarities. One such family is the AsnC/Lrp subfamily PMID:7770911. The Lrp family of transcriptional regulators appears to be widely distributed among bacteria and archaea, as an important regulatory system of the amino acid metabolism and related processes PMID:12675791.

Members of the Lrp family are small DNA-binding proteins with molecular masses of around 15kDa. The N-terminal part of the protein consists of a helix-turn-helix (HTH) domain, a fold generally involved in DNA binding. The C terminus of Lrp-like proteins has a beta-fold, where the two alpha-helices are located at one side of the four-stranded antiparallel beta-sheet. The C-terminal domain of Lrp-like proteins appears to be involved in ligand-response and activation PMID:12675791.

This entry represents the C-terminal effector binding or RAM domain of the transcription regulator AsnC/Lrp. Structurally this domain has a dimeric alpha/beta barrel fold PMID:7770911,PMID:17374605.