BIO315H5 Midterm: Test 1 Review - Lecture 4
Document Summary
Undergoes a conformational change when bound allosterically to calcium. Ser/thr kinase phosphorylates on the residues. Regulatory segment at active site of kinase blocks kinase activity & regulated by calmodulin. Each subunit has phosphorylation site ser/thr residue phosphorylated by camk- makes the kinase activity calcium independent. Each has 2 major domains: amino-terminal kinase (green) and carboxyl-terminal hub (blue) 6 camkii proteins are assembled surrounded by kinase domains. When the enzyme is inactive, the ring exists in a dynamic equilibrium between two states. Compact state kinase domains interact with hub, regulatory segment is buried in kinase active site and thereby blocks catalytic activity. Inactive state kinase domain has popped out and is linked to central hub by its regulatory segment, which continues to inhibit the kinase but is now accessible to ca2+/calmodulin. If present, ca2+/calmodulin will bind the regulatory segment and prevent it from inhibiting the kinase, thereby locking the kinase in an active state.
