Structure of the human red cell membrane showing the major surface proteins and minor proteins Fy and CR1. Two major membrane complexes linked to the underlying red cell skeleton are depicted. The Band 3 complex containing glycophorins A (GPA) and B (GPB) and Rh proteins, Rh-associated protein (RhAG), CD47, LW glycoprotein (intercellular adhesion molecule–4), and the junctional complex comprising glycophorins C and D (GPC, GPD), Kell glycoprotein, XK glycoprotein, and Duffy (Fy) glycoprotein. Aquaporin 1 (AQP1), the glucose transporter (GLUT1), decay accelerating factor (DAF, CD55), and complement receptor 1 (CR1) are also shown. ABH active oligosaccharides known to be present on all major surface proteins except Rh proteins are not depicted.