Feedback regulation of the polyamine transporter in mammalian cells
Polyamines are small, highly abundant organic cations that are found in all living cells. Internal polyamine concentrations in mammalian cells are under strict regulation. The main contributors to cellular polyamine levels are: a) de novo production via ornithine decarboxylase, and b) uptake from the extracellular fluids by active transport. Both of these processes are precisely regulated by feedback controls. Recent studies have begun to demonstrate the control of polyamine biosynthesis; however, the mechanism of regulation of the transporter was unknown until this study. The work described in this thesis demonstrates that the feedback regulation of the polyamine transporter is via a spermidine-induced labile protein.