Clustering of plasma membrane-bound cytochrome b5 reductase within ‘lipid raft’ microdomains of the neuronal plasma membrane

Plasma membrane redox centres play a major role in neuronal defence against oxidative stress and survival. In cerebellar granule neurons in culture (CGN) a large pool of the flavoproteins are associated with the plasma membrane, and the intensity of CGN green/orange autofluorescence correlated with the levels of expression of cytochrome b5 reductase. Regionalization of cytochrome b5 reductase in the plasma membrane of CGN by fluorescence resonance energy transfer points out the close proximity between cytochrome b5 reductase and the ‘lipid raft’ markers cholera toxin B and caveolin-2. This study unravels that membrane-bound cytochrome b5 reductase is largely enriched at interneuronal contact sites in the neuronal soma and associated with ‘lipid rafts’ of the CGN plasma membrane. We also show that cytochrome b5 reductase makes a large contribution to the NADH oxidase activity and to the red-shifted flavine fluorescence of purified rat brain synaptic plasma membranes. In conclusion, membrane-bound cytochrome b5 reductase forms a large mesh of redox centres associated with the neuronal plasma membrane.