13 September 1996
Vol 273, Issue 5281

About The Cover

Subunit contact region (subunits are purple and turquoise) of the unphosphorylated, inactive yeast enzyme glycogen phosphorylase, shown with bound inhibitor glucose-6-phosphate (atom cluster at middle left, phosphate colored light green). After phosphorylation of a threonine residue (atom cluster at bottom right), the amino-terminal segment (red ribbon) refolds and then interferes with inhibitor binding and activates the enzyme. See page 1539. [Image: Kai Lin and Peter K. Hwang]