Three-dimensional structure of phosphorylase kinase at 22 A resolution and its complex with glycogen phosphorylase b

Structure. 2002 Jan;10(1):33-41. doi: 10.1016/s0969-2126(01)00691-8.


Phosphorylase kinase (PhK) integrates hormonal and neuronal signals and is a key enzyme in the control of glycogen metabolism. PhK is one of the largest of the protein kinases and is composed of four types of subunit, with stoichiometry (alphabetagammadelta)(4) and a total MW of 1.3 x 10(6). PhK catalyzes the phosphorylation of inactive glycogen phosphorylase b (GPb), resulting in the formation of active glycogen phosphorylase a (GPa) and the stimulation of glycogenolysis. We have determined the three-dimensional structure of PhK at 22 A resolution by electron microscopy with the random conical tilt method. We have also determined the structure of PhK decorated with GPb at 28 A resolution. GPb is bound toward the ends of each of the lobes with an apparent stoichiometry of four GPb dimers per (alphabetagammadelta)(4) PhK. The PhK/GPb model provides an explanation for the formation of hybrid GPab intermediates in the PhK-catalyzed phosphorylation of GPb.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Enzyme Activation
  • Glycogen Phosphorylase, Muscle Form / metabolism*
  • Image Processing, Computer-Assisted
  • Microscopy, Electron / methods
  • Models, Biological
  • Phosphorylase Kinase / chemistry*
  • Phosphorylase Kinase / metabolism
  • Phosphorylase Kinase / ultrastructure
  • Protein Binding
  • Protein Structure, Quaternary*
  • Rabbits
  • Signal Transduction / physiology


  • Glycogen Phosphorylase, Muscle Form
  • Phosphorylase Kinase