STUDIES ON HUMAN PORIN .13. THE TYPE-1 VDAC PORIN 31HL BIOTINYLATED AT THE PLASMALEMMA OF TRYPAN BLUE EXCLUDING HUMAN B-LYMPHOCYTES

In 1989, we demonstrated for the first time the expression of the VDAC 'Porin 31HL' in the plasmalemma of human B lymphocytes, then giving f irst evidence of a multi-topological expression of VDAC, Meanwhile, da ta from this and other laboratories support our proposal of a multi-co mpartment distribution of the channel in mammalian tissues, Here, by b iotinylation of plasmalemma-integrated proteins of proven living B lym phocytes, followed by two-dimensional electrophoresis, immuno- and str eptavidin affinity blotting, we show that part of the channel molecule s can be labelled at the outer membrane of the cells, Thus, by a relev ant approach our results invalidate objections concerning putative cro ss-reactivity of anti-human Type-1 porin antibodies with non-VDAC prot eins at the outer cell membrane.