SHAPE OF SPECTRIN MOLECULES FROM HUMAN ERYTHROCYTE-MEMBRANES

Purified spectrin dimers and tetramers have been directly visualized by low-angle shadowing. The 9-S heterodimer is an asymmetric flexible molecule about 1000 Å in length, its constituent monomer polypeptides forming two strands which in many molecules are individually visible, lying partially separated from one another or twisting round each other in a loose double helix. The 12-S tetramer is formed by the end-to-end association of two heterodimers, without overlap. The protein bears no physical resemblance to myosin. © 1978.