L-DOPA decarboxylase association with membranes in mouse brain

This work presents evidence on the association of active DDC molecules with membranes in mammalian brain. L-DOPA decarboxylase (DDC) is generally cons idered to be a cytosolic enzyme. Membrane-associated DDC was detected by im munoblotting and enzymatic assay experiments. DDC activity and immunoreacti vity could be partially extracted from mammalian brain membranes by deterge nt. Fractionation of membranes by temperature-induced phase separation in T riton X-114, resulted in the recovery of membrane-associated DDC in separat ion phases where integral and hydrophobic membrane proteins separate. Treat ment of membranes with phosphatidylinositol-specific phospholipase C or pro teinase K, did not elute membrane-associated DDC activity, suggesting that a population of DDC molecules exist embedded within membranes. The elucidat ion of the functional significance of the enzyme's association with membran es could provide us with new information leading to the better understandin g of the biological pathways that DDC is involved in.