Phosphoglucan water dikinase (also known as alpha-glucan water dikinase), N-terminal CBM20 (carbohydrate-binding module, family 20) domain. This domain is found in the chloroplast-encoded phosphoglucan water dikinase, one of two enzymes involved in the phosphorylation of plant starches. In addition to the CBM20 domain, phosphoglucan water dikinase contains a C-terminal pyruvate binding domain. The CBM20 domain is found in a large number of starch degrading enzymes including alpha-amylase, beta-amylase, glucoamylase, and CGTase (cyclodextrin glucanotransferase). CBM20 is also present in proteins that have a regulatory role in starch metabolism in plants (e.g. alpha-amylase) or glycogen metabolism in mammals (e.g. laforin). CBM20 folds as an antiparallel beta-barrel structure with two starch binding sites. These two sites are thought to differ functionally with site 1 acting as the initial starch recognition site and site 2 involved in the specific recognition of appropriate regions of starch.
Jiyao W et al.(2023). "The conserved domain database in 2023.",