Figure 8.

Proposed mechanism for autoregulation of CT enzymatic activity and mRNA translation. The RNA-binding and catalytic functions of CT are sensitive to the metabolic state of the cell. During stationary phase when de novo fatty acid synthesis is unneeded, glucose and thus acetyl-CoA levels are low, allowing CT to bind the mRNA for its subunits, attenuating expression of the enzyme as well as enzymatic activity on remaining acetyl-CoA stores. During log phase growth membrane biogenesis is needed. Glucose is abundant, increasing the availability of acetyl-CoA for fatty acid synthesis. Acetyl-CoA binds to CT permitting translation of the mRNA for the α- and β-subunits. This ‘dimmer switch’ model gives the cell a means of rapid response to changes in cellular metabolic state.