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128  structures 5879  species 0  interactions 35725  sequences 69  architectures

Family: AsnC_trans_reg (PF01037)

Summary: Lrp/AsnC ligand binding domain

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Lrp/AsnC ligand binding domain Provide feedback

The l-leucine-responsive regulatory protein (Lrp/AsnC) family is a family of similar bacterial transcription regulatory proteins. The family is named after two E. coli proteins involved in regulating amino acid metabolism. This entry corresponds to the usually C-terminal regulatory ligand binding domain. Structurally this domain has a dimeric alpha/beta barrel fold [2].

Literature references

  1. Kyrpides NC, Ouzounis CA; , Trends Biochem Sci 1995;20:140-141.: The eubacterial transcriptional activator Lrp is present in the archaeon Pyrococcus furiosus. PUBMED:7770911 EPMC:7770911

  2. Ren J, Sainsbury S, Combs SE, Capper RG, Jordan PW, Berrow NS, Stammers DK, Saunders NJ, Owens RJ;, J Biol Chem. 2007;282:14655-14664.: The structure and transcriptional analysis of a global regulator from Neisseria meningitidis. PUBMED:17374605 EPMC:17374605

Internal database links

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR019887

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 [ PUBMED: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 [ PUBMED:12675791 ].

Members of the Lrp family are small DNA-binding proteins with molecular masses of around 15kDa. Target promoters often contain a number of binding sites that typically lack obvious inverted repeat elements, and to which binding is usually co-operative. LrpA from Pyrococcus furiosus is the first Lrp-like protein to date of which a three-dimensional structure has been solved. In the crystal structure LrpA forms an octamer consisting of four dimers. The structure revealed that 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. LrpA forms a homodimer mainly through interactions between the beta-strands of this C-terminal domain, and an octamer through further interactions between the second alpha-helix and fourth beta-strand of the motif. Hence, the C-terminal domain of Lrp-like proteins appears to be involved in ligand-response and activation [ PUBMED:12675791 ].

This entry represents the C-terminal regulatory ligand binding domain of the transcription regulator AsnC/Lrp. Structurally this domain has a dimeric alpha/beta barrel fold [ PUBMED:7770911 , PUBMED:17374605 ].

Domain organisation

Below is a listing of the unique domain organisations or architectures in which this domain is found. More...

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Pfam Clan

This family is a member of clan Dim_A_B_barrel (CL0032), which has the following description:

This superfamily of proteins possess a Ferredoxin-like fold. Pairs of these assemble into a beta barrel. The function of this barrel is quite varied and includes Muconolactone isomerase as well as monooxygenases.

The clan contains the following 28 members:

ABM AsnC_trans_reg AsnC_trans_reg2 Chalcone_N Chlor_dismutase Cyclase_polyket Dabb Dehydratase_hem DUF1330 DUF1428 DUF3291 DUF4188 DUF4242 DUF4937 Dyp_perox EthD FtsX_ECD GYD HapK MIase MmlI NapD NIPSNAP rhaM SchA_CurD SOR YCII ydhR


We store a range of different sequence alignments for families. As well as the seed alignment from which the family is built, we provide the full alignment, generated by searching the sequence database (reference proteomes) using the family HMM. We also generate alignments using four representative proteomes (RP) sets and the UniProtKB sequence database. More...

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We make a range of alignments for each Pfam-A family. You can see a description of each above. You can view these alignments in various ways but please note that some types of alignment are never generated while others may not be available for all families, most commonly because the alignments are too large to handle.

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Representative proteomes UniProt

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You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.

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HMM logos is one way of visualising profile HMMs. Logos provide a quick overview of the properties of an HMM in a graphical form. You can see a more detailed description of HMM logos and find out how you can interpret them here. More...


This page displays the phylogenetic tree for this family's seed alignment. We use FastTree to calculate neighbour join trees with a local bootstrap based on 100 resamples (shown next to the tree nodes). FastTree calculates approximately-maximum-likelihood phylogenetic trees from our seed alignment.

Note: You can also download the data file for the tree.

Curation and family details

This section shows the detailed information about the Pfam family. You can see the definitions of many of the terms in this section in the glossary and a fuller explanation of the scoring system that we use in the scores section of the help pages.

Curation View help on the curation process

Seed source: Pfam-B_773 (release 3.0)
Previous IDs: ASNC_trans_reg;
Type: Domain
Sequence Ontology: SO:0000417
Author: Finn RD , Bateman A
Number in seed: 217
Number in full: 35725
Average length of the domain: 72.90 aa
Average identity of full alignment: 21 %
Average coverage of the sequence by the domain: 46.97 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 57096847 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 25.0 25.0
Trusted cut-off 25.0 25.0
Noise cut-off 24.9 24.9
Model length: 75
Family (HMM) version: 23
Download: download the raw HMM for this family

Species distribution

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Colour assignments

Archea Archea Eukaryota Eukaryota
Bacteria Bacteria Other sequences Other sequences
Viruses Viruses Unclassified Unclassified
Viroids Viroids Unclassified sequence Unclassified sequence


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This visualisation provides a simple graphical representation of the distribution of this family across species. You can find the original interactive tree in the adjacent tab. More...

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The tree shows the occurrence of this domain across different species. More...


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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the AsnC_trans_reg domain has been found. There are 128 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein sequence.

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AlphaFold Structure Predictions