PROSITE documentation PDOC00686
Acyl-CoA-binding (ACB) domain signature and profile


Acyl-CoA-binding protein (ACBP) is a small (10 Kd) protein that binds medium- and long-chain acyl-CoA esters with very high affinity and may function as an intracellular carrier of acyl-CoA esters [1]. ACBP is also known as diazepam binding inhibitor (DBI) or endozepine (EP) because of its ability to displace diazepam from the benzodiazepine (BZD) recognition site located on the GABA type A receptor. It is therefore possible that this protein also acts as a neuropeptide to modulate the action of the GABA receptor [2].

ACBP is a highly conserved protein of about 90 residues that is found in all four eukaryotic kingdoms, Animalia, Plantae, Fungi and Protista, and in some eubacterial species [3].

Although ACBP occurs as a completely independent protein, intact ACB domains have been identified in a number of large, multifunctional proteins in a variety of eukaryotic species. These include large membrane-associated proteins with N-terminal ACB domains, multifunctional enzymes with both ACB and peroxisomal enoyl-CoA Delta(3), Delta(2)-enoyl-CoA isomerase domains, and proteins with both an ACB domain and ankyrin repeats (see <PDOC50088>) [3].

The ACB domain consists of four α-helices arranged in a bowl shape with a highly exposed acyl-CoA-binding site (see <PDB:1HBK>). The ligand is bound through specific interactions with residues on the protein, most notably several conserved positive charges that interact with the phosphate group on the adenosine-3'phosphate moiety, and the acyl chain is sandwiched between the hydrophobic surfaces of CoA and the protein [4].

ACBP belongs to a family that also includes:

  • Endozepine-like peptide (ELP) (gene DBIL5) from mouse [5]. ELP is a testis- specific ACBP homolog that may be involved in the energy metabolism of the mature sperm.
  • MA-DBI, a transmembrane protein of unknown function which has been found in mammals. MA-DBI contains a N-terminal ACB domain.
  • DRS-1 [6], a human protein of unknown function that contains a N-terminal ACB domain and a C-terminal enoyl-CoA isomerase/hydratase domain.

As a signature pattern we selected the region that corresponds to residue 19 to 37 in mammalian ACBP. We also developed a profile which covers the entire ACB domain.

Last update:

July 2006 / Text revised; profile added.


Technical section

PROSITE methods (with tools and information) covered by this documentation:

ACB_2, PS51228; Acyl-CoA-binding (ACB) domain profile  (MATRIX)

ACB_1, PS00880; Acyl-CoA-binding (ACB) domain signature  (PATTERN)


1AuthorsRose T.M. Schultz E.R. Todaro G.J.
TitleMolecular cloning of the gene for the yeast homolog (ACB) of diazepam binding inhibitor/endozepine/acyl-CoA-binding protein.
SourceProc. Natl. Acad. Sci. U.S.A. 89:11287-11291(1992).
PubMed ID1454809

2AuthorsCosta E. Guidotti A.
TitleDiazepam binding inhibitor (DBI): a peptide with multiple biological actions.
SourceLife Sci. 49:325-344(1991).
PubMed ID1649940

3AuthorsBurton M. Rose T.M. Faergeman N.J. Knudsen J.
TitleEvolution of the acyl-CoA binding protein (ACBP).
SourceBiochem. J. 392:299-307(2005).
PubMed ID16018771

4Authorsvan Aalten D.M.F. Milne K.G. Zou J.Y. Kleywegt G.J. Bergfors T. Ferguson M.A.J. Knudsen J. Jones T.A.
TitleBinding site differences revealed by crystal structures of Plasmodium falciparum and bovine acyl-CoA binding protein.
SourceJ. Mol. Biol. 309:181-192(2001).
PubMed ID11491287

5AuthorsPusch W. Balvers M. Hunt N. Ivell R.
TitleA novel endozepine-like peptide (ELP) is exclusively expressed in male germ cells.
SourceMol. Cell. Endocrinol. 122:69-80(1996).
PubMed ID8898349

6AuthorsSuk K. Kim Y.-H. Hwang D.-Y. Ihm S.H. Yoo H.J. Lee M.S.
TitleMolecular cloning and expression of a novel human cDNA related to the diazepam binding inhibitor.
SourceBiochim. Biophys. Acta 1454:126-131(1999).
PubMed ID10354522

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