XANTHINE OXIDOREDUCTASE IS ASYMMETRICALLY LOCALIZED ON THE OUTER SURFACE OF HUMAN ENDOTHELIAL AND ENDOTHELIAL-CELLS IN CULTURE

Subcellular localisation of xanthine oxidoreductase (XOR) was determin ed by indirect immunofluorescence using confocal microscopy in human e ndothelial and epithelial cell lines and in primary cultures of human umbilical vein endothelial cells. XOR was diffusely distributed throug hout the cytoplasm but with higher intensity in the perinuclear region . In non-permeabilised cells, XOR was clearly seen to be asymmetricall y located on the outer surfaces, showing, in many cases, a higher inte nsity on those faces apposed by closely neighbouring cells. Such speci fic distribution suggests a functional role for the enzyme in cell-cel l interactions, possibly involving signalling via reactive oxygen spec ies. (C) 1998 Federation of European Biochemical Societies.