Evidence for erythrocyte membrane glycoproteins being carriers of blood-group P1 determinants

The contribution of different membrane constituents to the bloodgroup P₁ activity of human erythrocytes was investigated. Pronase digestion of native red cell stroma or partition between butanol and water had no serologically detectable effect, whereas pronase-treatment of previously butanol-extracted membranes liberated virtually all blood-group P₁ determinants from the ghosts. On Laemmli gels, all P₁ activity was found in the band 4.5 region. Thus it is concluded that, in addition to the well-documented P₁ glycolipid, also membrane glycoproteins are carriers of blood-group P₁ determinants.