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65  structures 8001  species 0  interactions 70903  sequences 854  architectures

Family: ABC2_membrane (PF01061)

Summary: ABC-2 type transporter

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This is the Wikipedia entry entitled "ATP-binding cassette transporter". More...

ATP-binding cassette transporter Edit Wikipedia article

'ATP binding cassette (ABC) transporters are transporting various material over membranes, for example the inner mitochondrial membrane.

Category: Biology->Biochemistry/Microbiology

This page is based on a Wikipedia article. The text is available under the Creative Commons Attribution/Share-Alike License.

This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.

ABC-2 type transporter Provide feedback

No Pfam abstract.

Literature references

  1. Reizer J, Reizer A, Saier MH Jr; , Protein Sci 1992;1:1326-1332.: A new subfamily of bacterial ABC-type transport systems catalyzing export of drugs and carbohydrates. PUBMED:1303751 EPMC:1303751

Internal database links

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR013525

ABC transporters belong to the ATP-Binding Cassette (ABC) superfamily, which uses the hydrolysis of ATP to energise diverse biological systems. ABC transporters minimally consist of two conserved regions: a highly conserved ATP binding cassette (ABC) and a less conserved transmembrane domain (TMD). These can be found on the same protein or on two different ones. Most ABC transporters function as a dimer and therefore are constituted of four domains, two ABC modules and two TMDs.

ABC transporters are involved in the export or import of a wide variety of substrates ranging from small ions to macromolecules. The major function of ABC import systems is to provide essential nutrients to bacteria. They are found only in prokaryotes and their four constitutive domains are usually encoded by independent polypeptides (two ABC proteins and two TMD proteins). Prokaryotic importers require additional extracytoplasmic binding proteins (one or more per systems) for function. In contrast, export systems are involved in the extrusion of noxious substances, the export of extracellular toxins and the targeting of membrane components. They are found in all living organisms and in general the TMD is fused to the ABC module in a variety of combinations. Some eukaryotic exporters encode the four domains on the same polypeptide chain [ PUBMED:9873074 ].

The ABC module (approximately two hundred amino acid residues) is known to bind and hydrolyse ATP, thereby coupling transport to ATP hydrolysis in a large number of biological processes. The cassette is duplicated in several subfamilies. Its primary sequence is highly conserved, displaying a typical phosphate-binding loop: Walker A, and a magnesium binding site: Walker B. Besides these two regions, three other conserved motifs are present in the ABC cassette: the switch region which contains a histidine loop, postulated to polarise the attaching water molecule for hydrolysis, the signature conserved motif (LSGGQ) specific to the ABC transporter, and the Q-motif (between Walker A and the signature), which interacts with the gamma phosphate through a water bond. The Walker A, Walker B, Q-loop and switch region form the nucleotide binding site [ PUBMED:11421269 , PUBMED:1282354 , PUBMED:9640644 ].

The 3D structure of a monomeric ABC module adopts a stubby L-shape with two distinct arms. ArmI (mainly beta-strand) contains Walker A and Walker B. The important residues for ATP hydrolysis and/or binding are located in the P-loop. The ATP-binding pocket is located at the extremity of armI. The perpendicular armII contains mostly the alpha helical subdomain with the signature motif. It only seems to be required for structural integrity of the ABC module. ArmII is in direct contact with the TMD. The hinge between armI and armII contains both the histidine loop and the Q-loop, making contact with the gamma phosphate of the ATP molecule. ATP hydrolysis leads to a conformational change that could facilitate ADP release. In the dimer the two ABC cassettes contact each other through hydrophobic interactions at the antiparallel beta-sheet of armI by a two-fold axis [ PUBMED:11988180 , PUBMED:11470432 , PUBMED:11402022 , PUBMED:9872322 , PUBMED:11080142 , PUBMED:11532960 ].

The ATP-Binding Cassette (ABC) superfamily forms one of the largest of all protein families with a diversity of physiological functions [ PUBMED:9873074 ]. Several studies have shown that there is a correlation between the functional characterisation and the phylogenetic classification of the ABC cassette [ PUBMED:9873074 , PUBMED:11421270 ]. More than 50 subfamilies have been described based on a phylogenetic and functional classification [ PUBMED:9873074 , PUBMED:11421269 , PUBMED:11421270 ].

A number of bacterial transport systems have been found to contain integral membrane components that have similar sequences [ PUBMED:1303751 ]: these systems fit the characteristics of ATP-binding cassette transporters [ PUBMED:1659649 ]. The proteins form homo- or hetero-oligomeric channels, allowing ATP-mediated transport. Hydropathy analysis of the proteins has revealed the presence of 6 possible transmembrane regions. These proteins belong to family 2 of ABC transporters.

Gene Ontology

The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.

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 ABC-2 (CL0181), which has the following description:

These families are similar to the ABC-2 transporter subfamily, as described in [1] (Pfam:PF01061). Members of this family are involved in drug transport and resistance. CcmB protein family (Pfam:PF03379) members are also transporters; they are required for haem export into the periplasm [2].

The clan contains the following 17 members:

12TM_1 ABC2_membrane ABC2_membrane_2 ABC2_membrane_3 ABC2_membrane_4 ABC2_membrane_5 ABC2_membrane_6 ABC2_membrane_7 ABC_export ABC_tran_2 CcmB DUF2705 DUF3526 DUF3533 DUF6198 PDR_CDR YitT_membrane


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_865 (release 3.0) & Pfam-B_31 (release 15.0)
Previous IDs: none
Type: Family
Sequence Ontology: SO:0100021
Author: Finn RD , Bateman A
Number in seed: 214
Number in full: 70903
Average length of the domain: 205 aa
Average identity of full alignment: 16 %
Average coverage of the sequence by the domain: 40.1 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 61295632 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 26.9 26.9
Trusted cut-off 26.9 26.9
Noise cut-off 26.8 26.8
Model length: 210
Family (HMM) version: 27
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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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 ABC2_membrane domain has been found. There are 65 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

The list of proteins below match this family and have AlphaFold predicted structures. Click on the protein accession to view the predicted structure.

Protein Predicted structure External Information
A0A044TYF6 View 3D Structure Click here
A0A044UYQ6 View 3D Structure Click here
A0A059J0G5 View 3D Structure Click here
A0A077ZCK3 View 3D Structure Click here
A0A077ZEH5 View 3D Structure Click here
A0A0D2DIW5 View 3D Structure Click here
A0A0D2DSD2 View 3D Structure Click here
A0A0D2F572 View 3D Structure Click here
A0A0D2FCC2 View 3D Structure Click here
A0A0D2FHA4 View 3D Structure Click here
A0A0D2GFN8 View 3D Structure Click here
A0A0D2GI56 View 3D Structure Click here
A0A0D2GRZ1 View 3D Structure Click here
A0A0D2GU55 View 3D Structure Click here
A0A0D2HI66 View 3D Structure Click here
A0A0H3GMQ5 View 3D Structure Click here
A0A0H3GSI2 View 3D Structure Click here
A0A0K0E614 View 3D Structure Click here
A0A0K0E6J2 View 3D Structure Click here
A0A0K0ECK1 View 3D Structure Click here
A0A0K0EIA7 View 3D Structure Click here
A0A0K0EQB8 View 3D Structure Click here
A0A0N4UJH6 View 3D Structure Click here
A0A0N4UK82 View 3D Structure Click here
A0A0N7KF66 View 3D Structure Click here
A0A0P0V2F0 View 3D Structure Click here
A0A0P0V3M7 View 3D Structure Click here
A0A0P0VIB9 View 3D Structure Click here
A0A0P0VM04 View 3D Structure Click here
A0A0P0XK84 View 3D Structure Click here
A0A0P0XLR2 View 3D Structure Click here
A0A0P0XN42 View 3D Structure Click here
A0A0P0XZV4 View 3D Structure Click here
A0A0P0Y9Q9 View 3D Structure Click here
A0A0R0EXX2 View 3D Structure Click here
A0A0R0EYV9 View 3D Structure Click here
A0A0R0FFZ5 View 3D Structure Click here
A0A0R0G2G7 View 3D Structure Click here
A0A0R0GI77 View 3D Structure Click here
A0A0R0GIB2 View 3D Structure Click here