HEMOGLOBIN-SPECTRIN COMPLEXES - INTERFERENCE WITH SPECTRIN TETRAMER ASSEMBLY AS A MECHANISM FOR COMPARTMENTALIZATION OF BAND-1 AND BAND-2 COMPLEXES

The irreducible complexation of hemoglobin with spectrin is a natural phenomenon of red blood cell aging, positively correlating with increa sing cell density and decreasing cell deformability. The current study begins to address the role of these complexes in the disruption of me mbrane skeletal physiology and structure, The effect of bound hemoglob in on spectrin dimer self-association was investigated in vitro. The e xtent of conversion of isolated spectrin dimers to tetramers was evalu ated as a function of peroxide-induced globin complexation before the conversion incubations. The incremental accumulation of tetramer was o bserved to decrease with increasing peroxide concentration used in the globin complexation step. The role of oxidized heme in this process w as made apparent by the inability of carboxyhemoglobin to inhibit tetr amer accumulation. A Western blot analysis of naturally formed globin- spectrin conjugates demonstrated irreducible complexes of globin with both bands 1 and 2. The complexes are tentatively designated ''h1'' an d ''h2''. This analysis also demonstrated that hi is completely extrac table from cell ghosts, whereas h2 is only 50% extractable, These find ings are incorporated into a hypothesis linking globin-spectrin comple xation and the consequent inhibition of spectrin dimer self-associatio n to the clustered band 3 senescence antigen (Low et al, Science 227:5 31, 1985). (C) 1995 by The American Society of Hematology.