Clustering of plasma membrane-bound cytochrome b 5 reductase within ‘lipid raft’ microdomains of the neuronal plasma membrane

Abstract

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 b 5 reductase. Regionalization of cytochrome b 5 reductase in the plasma membrane of CGN by fluorescence resonance energy transfer points out the close proximity between cytochrome b 5 reductase and the ‘lipid raft’ markers cholera toxin B and caveolin-2. This study unravels that membrane-bound cytochrome b 5 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 b 5 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 b 5 reductase forms a large mesh of redox centres associated with the neuronal plasma membrane.