Spectrin oligomers: a structural feature of the erythrocyte cytoskeleton.

Spectrin reversibly self-associates to high molecular weight oligomers through a concentration-driven process characterized by association constants of about 10(5) mol(-1). This association if prominent under physiological conditions of pH, ionic strength, and temperature. It is disrupted by urea, but not Triton X-100. The process of spectrin association appears mathematically to resemble that for tropomyosin, although the mechanism is probably different. Spectrin association is weak compared to other prominent protein-protein associations in the red cell membrane skeleton. The linkage of these weak and strong associations suggests a process whereby the membrane skeleton spontaneously assembles. Such affinity-modulated assembly involving weak associations is likely to abe the focus of numerous membrane.