Family 2.A.59 - The Arsenical Resistance-3 Family
Family ID: 53379
A single protein of the ACR3 family has been functionally characterized.
This protein is the ACR3 protein of Saccharomyces cerevisiae.
It is present in the yeast plasma membrane and pumps arsenite,
but not arsenate, antimony, tellurite, cadmium or phenylarsine
oxide out of the cell in response to the pmf. The exact transport
mechanism is not established, but a uniport mechanism seems likely.
ACR3 of S.
cerevisiae is 404 amino acyl residues long and exhibits 10 putative
transmembrane a-helical spanners (TMSs). Homologues are found
in Mycobacterium tuberculosis (498aas; gbZ80225), Bacillus subtilis
(346aas; spP45946), Archaeoglobus fulgidus (370aas; gbAE001071),
Methanobacterium thermoautotrophicum (365aas; gbAE000865) and
Synechocystis (383aas; spP74311). The Bacillus and Synechocystis
proteins exhibit 11 and 10 putative TMSs, respectively. Thus,
members of the ACR3 family are found in bacteria, archaea and
eukarya. Limited sequence similarity of the Synechocystis protein
with the human bile acid:Na+ cotransporter NTCP (spQ14973) has
been noted, but this similarity is insufficient to establish homology.
