Phospholipid asymmetry in microsomal membranes of human brain tumors.

Phospholipid topology in human brain tumor microsomes was investigated by the use of specific aminophospholipid tracer, trinitrobenzenesulfonic acid, and by phospholipase hydrolysis method. In non-neoplastic brain cortex and white matter the outer leaflet of the bilayer contains predominantly phosphatidylcholine and the inner leaflet mostly phosphatidylethanolamine and phosphatidylserine. Sphingomyelin is equally distributed between the two leaflets. In microsomes from glioma and meningioma tumors, a significant decrease in phosphatidylcholine and sphingomyelin at the outer surface was observed.