Peroxisomal ABC proteins

The ABC protein family:

ATP-binding cassette (ABC) proteins form one of the largest protein families. Members of this family have been found in each organism examined so far, including bacteria and plants. At least 48 human ABC proteins have been identified in the human genome. Many of these ABC proteins are active transmembrane pumps, they can transport substrates against the concentration gradient. The energy needed for this active transport is generated through the hydrolysis of ATP.

The general structure of a functional "full ABC transporter" consists of two transmembrane domains (TMD), each composed of six transmembrane helices, and two ABC units. There are several different arrangements of the TMD and ABC domains found among the human ABC proteins. In general, a full functional transporter is build up following the TMD-ABC-TMD-ABC composition. The four domains may be present in one polypeptide (like the MDR P-glycoproteins), or they can be formed by a multiprotein complex (like TAP1 (ABCB2) and TAP2 (ABCB3)).

There is a website available at NCBI devoted to ABC genes written by Dr Michael Dean. It has descriptions and references to all the human, mouse and ABC Drosophila genes with links to OMIM, LocusLink, mouse genome database, chromosome maps, etc. Best of all, you can also download the entire text as a PDF file. The site will be updated periodically and may eventually even contain links to other sites, videos, lectures, figures that never got published. Follow this link

The peroxisomal ABC proteins (ABCD):

The X-ALD protein (ALDP) consists of 745 amino acids and has the topology of a "half ABC transporter", it contains only one transmembrane domain and one ATP-binding unit (TMD-ABC). It is likely that in order to become a "full transporter" ALDP has to form a dimer, either with itself of with one of the other peroxisomal half ABC proteins. In vitro ALDP homodimerization and heterodimerization of ALDP with either ALDRP or PMP70 has been demonstrated (Smith et al., 1999; Lui et al., 1999). The peroxisomal half ABC transporters ALDP, adrenoleukodystrophy-related protein (ALDRP) and the 70 kDa peroxisomal membrane protein (PMP70) form a separate subclass of the ABC proteins (subclass D). See also Phylogenetic analysis of peroxisomal ABC proteins

For more information: Follow this link.

Last update: 04-Feb-2010