It has been shown [1,2,3,E1] that the following glycosyl hydrolases can be, on
the basis of sequence similarities, classified into a single family:
Lysosomal α-glucosidase (EC 220.127.116.11) (acid maltase) is a vertebrate
glycosidase active at low pH, which hydrolyzes α(1->4) and α(1->6)
linkages in glycogen, maltose, and isomaltose.
α-glucosidase (EC 18.104.22.168) from the yeast Candida tsukunbaensis.
α-glucosidase (EC 22.214.171.124) (gene malA) from the archebacteria
Intestinal sucrase-isomaltase (EC 126.96.36.199 / EC 188.8.131.52) is a vertebrate
membrane-bound, multifunctional enzyme complex which hydrolyzes sucrose,
maltose and isomaltose. The sucrase and isomaltase domains of the enzyme
are homologous (41% of amino acid identity) and have most probably evolved
Glucoamylase 1 (EC 184.108.40.206) (glucan 1,4-α-glucosidase) from various
Yeast hypothetical protein YBR229c.
Fission yeast hypothetical protein SpAC30D11.01c.
An aspartic acid has been implicated  in the catalytic activity of sucrase,
isomaltase, and lysosomal α-glucosidase. The region around this active
residue is highly conserved and can be used as a signature pattern. We have
used a second region, which contains two conserved cysteines, as an additional
Striking structural and functional similarities suggest that intestinal sucrase-isomaltase, human lysosomal alpha-glucosidase and Schwanniomyces occidentalis glucoamylase are derived from a common ancestral gene.
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