BetaGal_dom2

Beta-galactosidase, domain 2
BetaGal_dom2
SMART accession number:SM01029
Description: This is the second domain of the five-domain beta-galactosidase enzyme that altogether catalyses the hydrolysis of beta(1-3) and beta(1-4) galactosyl bonds in oligosaccharides as well as the inverse reaction of enzymatic condensation and trans-glycosylation. This domain is made up of 16 antiparallel beta-strands and an alpha-helix at its C terminus. The fold of this domain appears to be unique. In addition, the last seven strands of the domain form a subdomain with an immunoglobulin-like (I-type Ig) fold in which the first strand is divided between the two beta-sheets. In penicillin spp this strand is interrupted by a 12-residue insertion which forms an additional edge-strand to the second beta-sheet of the sub-domain. The remainder of the second domain forms a series of beta-hairpins at its N terminus, four strands of which are contiguous with part of the Ig-like sub-domain, forming in total a seven-stranded antiparallel beta-sheet. This domain is associated with family Glyco_hydro_35, which is N-terminal to it, but itself has no metazoan members.
Interpro abstract (IPR018954):

This is the second domain of the five-domain beta-galactosidase enzyme that altogether catalyses the hydrolysis of beta(1-3) and beta(1-4) galactosyl bonds in oligosaccharides as well as the inverse reaction of enzymatic condensation and trans-glycosylation. This domain is made up of 16 antiparallel beta-strands and an alpha-helix at its C terminus. The fold of this domain appears to be unique. In addition, the last seven strands of the domain form a subdomain with an immunoglobulin-like (I-type Ig) fold in which the first strand is divided between the two beta-sheets. In penicillin spp this strand is interrupted by a 12-residue insertion which forms an additional edge-strand to the second beta-sheet of the sub-domain. The remainder of the second domain forms a series of beta-hairpins at its N terminus, four strands of which are contiguous with part of the Ig-like sub-domain, forming in total a seven-stranded antiparallel beta-sheet.

Family alignment:
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There are 102 BetaGal_dom2 domains in 102 proteins in SMART's nrdb database.

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