||The enzyme phosphorylates granular starch that has previously been phosphorylated by EC 126.96.36.199, α-glucan, water dikinase; there is no activity with unphosphorylated glucans. It transfers the β-phosphate of ATP to the phosphoglucan, whereas the γ-phosphate is transferred to water . In contrast to EC 188.8.131.52, which phosphorylates glucose groups in glucans on O-6, this enzyme phosphorylates glucose groups in phosphorylated starch on O-3 . The protein phosphorylates itself with the β-phosphate of ATP, which is then transferred to the glucan .
||Kötting, O., Pusch, K., Tiessen, A., Geigenberger, P., Steup, M. and Ritte, G. Identification of a novel enzyme required for starch metabolism in Arabidopsis leaves. The phosphoglucan, water dikinase. Plant Physiol. 137 (2005) 242–252. [PMID: 15618411]
||Ritte, G., Heydenreich, M., Mahlow, S., Haebel, S., Kötting, O. and Steup, M. Phosphorylation of C6- and C3-positions of glucosyl residues in starch is catalysed by distinct dikinases. FEBS Lett. 580 (2006) 4872–4876. [PMID: 16914145]