PROSITE documentation PDOC00531 [for PROSITE entry PS00719]
Glycosyl hydrolases family 2 signatures


It has been shown [1,2,E1] that the following glycosyl hydrolases can be, on the basis of sequence similarities, classified into a single family:

  • β-galactosidases (EC from bacteria such as Escherichia coli (genes lacZ and ebgA), Clostridium acetobutylicum, Clostridium thermosulfurogenes, Klebsiella pneumoniae, Lactobacillus delbrueckii, or Streptococcus thermophilus and from the fungi Kluyveromyces lactis.
  • β-glucuronidase (EC from Escherichia coli (gene uidA) and from mammals.

One of the conserved regions in these enzymes is centered on a conserved glutamic acid residue which has been shown [3], in Escherichia coli lacZ, to be the general acid/base catalyst in the active site of the enzyme. We have used this region as a signature pattern. As a second signature pattern we selected a highly conserved region located some sixty residues upstream from the active site glutamate.

Expert(s) to contact by email:

Henrissat B.

Last update:

April 2006 / Pattern revised.


Technical section

PROSITE methods (with tools and information) covered by this documentation:

GLYCOSYL_HYDROL_F2_1, PS00719; Glycosyl hydrolases family 2 signature 1  (PATTERN)

GLYCOSYL_HYDROL_F2_2, PS00608; Glycosyl hydrolases family 2 acid/base catalyst  (PATTERN)


1AuthorsHenrissat B.
TitleA classification of glycosyl hydrolases based on amino acid sequence similarities.
SourceBiochem. J. 280:309-316(1991).
PubMed ID1747104

2AuthorsSchroeder C.J. Robert C. Lenzen G. McKay L.L. Mercenier A.
TitleAnalysis of the lacZ sequences from two Streptococcus thermophilus strains: comparison with the Escherichia coli and Lactobacillus bulgaricus beta-galactosidase sequences.
SourceJ. Gen. Microbiol. 137:369-380(1991).
PubMed ID1901904

3AuthorsGebler J.C. Aebersold R. Withers S.G.
TitleGlu-537, not Glu-461, is the nucleophile in the active site of (lac Z) beta-galactosidase from Escherichia coli.
SourceJ. Biol. Chem. 267:11126-11130(1992).
PubMed ID1350782


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