G. Fairbanks, f Theodore L. Steck, § and D. F. H. Wallach/: abstract: The polypeptides of the human erythrocyte mem-brane were analyzed by polyacrylamide gel electrophoresis in

1% sodium dodecyl sulfate. Six major bands (I-VI) together make up over two-thirds of the protein staining profile. Component III (mol wt89, 000) predominates in the ghost mem-brane; it constitutes 30% of the protein and numbers over 106 chains/ghost. Components I and II form a slow-moving doublet (approximate mol wt250, 000) containing 25% of the protein. The molar amounts of I+ II, IV (mol wt 77,500), V (mol wt 41,300), and VI (mol wt 36,200) are similar, falling in the range 3.4-4.6 X 105 chains/ghost. Four bands were recognized in gels stained by the periodicacid-Schiff procedure. A broad Schiff-positive zone just behind the tracking dye corresponds to membrane lipids. Three bands of lower mobil-ity are sialoglycoproteins. The most prominent of these has an apparent molecular weight of 83,500 andcontains at least 57% of the sialic acid of ghosts. The Schiff-positive bands were not colored by protein stains. Sialidase treatment of ghosts selectively increased the mobilities of the sialoglycoproteins without affecting the protein-staining profile. At-tempts to produce subunits from the large polypeptides by treatment with various denaturing agents were unsuccessful. Normally, no polypeptides of size less than 15,000 were seen