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

Journal article

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.

Authors: Vénien-Bryan, C; Lowe, E; Boisset, N; Traxler, K; Johnson, L

• Publication status: Published
• Journal: Structure (London, England : 1993)
• Volume: 10
• Issue: 1
• Pages: 33-41
• Publication date: 2002-01-01
• DOI: 10.1016/s0969-2126(01)00691-8
• EISSN: 1878-4186
• ISSN: 0969-2126
• Language: English
• Keywords: Rabbits; Signal Transduction; Protein Structure, Quaternary; Glycogen Phosphorylase, Muscle Form; Phosphorylase Kinase; Image Processing, Computer-Assisted; Protein Binding; Microscopy, Electron; Models, Biological; Enzyme Activation; Animals