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alpha-1,4-glucan:alpha-1,4-glucan 6-glycosyltransferase This model describes the glycogen branching enzymes which are responsible for the transfer of chains of approx. 7 alpha(1--4)-linked glucosyl residues to other similar chains (in new alpha(1--6) linkages) in the biosynthesis of glycogen. This enzyme is a member of the broader amylase family of starch hydrolases which fold as (beta/alpha)8 barrels, the so-called TIM-barrel structure. All of the sequences comprising the seed of this model have been experimentally characterized. This model encompasses both bacterial and eukaryotic species. No archaea have this enzyme, although Aquifex aolicus does. Two species, Bacillus thuringiensis and Clostridium perfringens have two sequences each which are annotated as amylases. These annotations are aparrently in error. GP|18143720 from C. perfringens, for instance, contains the note "674 aa, similar to gp:A14658_1 amylase (1,4-alpha-glucan branching enzyme (EC 2.4.1.18) ) from Bacillus thuringiensis (648 aa); 51.1% identity in 632 aa overlap." A branching enzyme from Porphyromonas gingivales, OMNI|PG1793, appears to be more closely related to the eukaryotic species (across a deep phylogenetic split) and may represent an instance of lateral transfer from this species' host. A sequence from Arabidopsis thaliana, GP|9294564, scores just above trusted, but appears either to contain corrupt sequence or, more likely, to be a pseudogene as some of the conserved catalytic residues common to the alpha amylase family are not conserved here. [Energy metabolism, Biosynthesis and degradation of polysaccharides] |
Jiyao W et al.(2023). "The conserved domain database in 2023.",