Mediates the incorporation of phosphate into starch-like alpha-glucan, mostly at the C-6 position of glucose units. Acts as an overall regulator of starch mobilization. Required for starch degradation, suggesting that the phosphate content of starch regulates its degradability. More active on alpha-1,6 branched amylopectin. [(1->4)-alpha-D-glucosyl](n) + n ATP + n H2O = [(1->4)-6-phospho-alpha-D-glucosyl](n) + n AMP + 2n H(+) + n phosphate ATP + protein L-histidine = ADP + protein N-phospho-L-histidine. Optimum pH is 7. Optimum temperature is 35 degrees Celsius. Homodimer. Starch granules. Binds to starch granules isolated from either illuminated or darkened leaves. However, binding to darkened leaves is more effective, suggesting that depending upon the metabolic state of the cells, the starch granule surface changes and thereby affects its binding. Expressed in leaves. The N-terminal domain contains the alpha-glucan binding site, the central domain the pyrophosphate/phosphate carrier histidine, and the C-terminal domain the ATP binding site. The reaction takes place in three steps, mediated by a phosphocarrier histidine residue located on the surface of the central domain. The two first partial reactions are catalyzed at an active site located on the C-terminal domain, and the third partial reaction is catalyzed at an active site located on the N-terminal domain. For catalytic turnover, the central domain swivels from the concave surface of the C-terminal domain to that of the N-terminal domain. Belongs to the PEP-utilizing enzyme family.