The ABCA subclass of mammalian transporters

We describe here a subclass of mammalian ABC transporters, the ABCA subfami ly. This is a unique group that, in contrast to any other human ABC transpo rters, lacks a structural counterpart in yeast. The structural hallmark of the ABCA subfamily is the presence of a stretch of hydrophobic amino acids thought to span the membrane within the putative regulatory (R) domain. As for today, four ABCA transporters have been fully characterised but 11 ABCA -encoding genes have been identified. AECA-specific motifs in the nucleotid e binding folds can be detected when analysing the conserved sequences amon g the different members. These motifs may reveal functional constraints exc lusive to this group of ABC transporters. (C) 1999 Elsevier Science B.V. Al l rights reserved.