Human platelet phosphorylase

Glycogenesis and glyconeogenesis in human platelets

“…3). The newly synthesized glycogen is also available to the degradative glycogenolytic enzymes, phosphorylase (which has been described in human platelets, 4,5,14), and probable amylo-1,6 glucosidase (which could be predicted) since The fructose-1,6-diphosphatase activity of human platelets appears unique in its modulation by AMP, ADP, and ATP and lack of requirement for Mg"+ ion. AMP, in contrast to its inhibitory effect on other fructose-1,6-diphosphatases (10,(11)(12)(13), activates the platelet enzyme.…”

“…3). The specific activity of the inner core increased exponentially as would be expected if new glucosyl units were deposited on already existent glycogen branches, some of which were then converted to 1-6 linkages (followed by [1][2][3][4] …”

“…Glycogenolysis in human platelets represents approximately 50% of glycolytic flux through the EmbdenMeyerhof pathway in the presence of physiologic concentrations of glucose (1,3). Human platelets contain a glycogen degradative enzyme, phosphorylase, which is similar in some respects to that of skeletal muscle (4) but different in other respects (5).…”