title: Characterization of the ABCA transporter subfamily: identification of prokaryotic and eukaryotic members, phylogeny and topology.
abstract: An alignment of the mammalian ABCA transporters enabled the identification of sequence segments, specific to the ABCA subfamily, which were used as queries to search for eukaryotic and prokaryotic homologues. Thirty-seven eukaryotic half and full-length transporters were found, and a close relationship with prokaryotic subfamily 7 transporters was detected. Each half of the ABCA full-transporters is predicted to comprise a membrane-spanning domain (MSD) composed of six helices and a large extracellular loop, followed by a nucleotide-binding domain (NBD) and a conserved cytoplasmic 80-residue sequence, which might have a regulatory function. The topology predicted for the ABCA transporters was compared to the crystal structures of the MsbA and BtuCD bacterial transporters. The alignment of the MSD and NBD domains provided an estimate of the degree of residue conservation in the cytoplasmic, extracellular and transmembrane domains of the ABCA transporter subfamily. The phylogenic tree of eukaryotic ABCA transporters based upon the NBD sequences, consists of three major clades, corresponding to the half-transporter single NBDs and to the full-transporter NBDls and NBD2s. A phylogenic tree of prokaryotic transporters and the eukaryotic ABCA transporters confirmed the evolutionary relationship between prokaryotic subfamily 7 transporters and eukaryotic ABCA half and full-transporters.
authors.affiliation: Laboratory for Lipoprotein Chemistry, Faculty of Medicine, Department of Biochemistry, Ghent University, Belgium.
authors.forename: Frank
authors.initials: F
authors.lastname: Peelman
authors.forename: Christine
authors.initials: C
authors.lastname: Labeur
authors.forename: Berlinda
authors.initials: B
authors.lastname: Vanloo
authors.forename: Stein
authors.initials: S
authors.lastname: Roosbeek
authors.forename: Catherine
authors.initials: C
authors.lastname: Devaud
authors.forename: Nicolas
authors.initials: N
authors.lastname: Duverger
authors.forename: Patrice
authors.initials: P
authors.lastname: Denèfle
authors.forename: Marie
authors.initials: M
authors.lastname: Rosier
authors.forename: Joël
authors.initials: J
authors.lastname: Vandekerckhove
authors.forename: Maryvonne
authors.initials: M
authors.lastname: Rosseneu
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry / Q000145:classification* / Q000235:genetics* / Q000378:metabolism; D000465:Algorithms; D000595:Amino Acid Sequence; D000818:Animals; D016208:Databases, Factual; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D011387:Prokaryotic Cells / Q000737:chemistry* / Q000502:physiology; D011487:Protein Conformation; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D018528:ATP-Binding Cassette Transporters; D015800:Protozoan Proteins; D014764:Viral Proteins