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Band 3 rotation in the human erythrocyte membrane is measured by observing flash-induced dichroism of eosin probes. The decay of the absorption anisotropy is found to be strongly dependent on temperature. The results are analyzed on the assumption that rotation of band 3 only occurs about the membrane normal. It is deduced that both fast and slowly rotating forms of band 3 coexist in the membrane. The equilibrium between these forms is temperature dependent, the slowly rotating species becoming increasingly dominant as the temperature is reduced. Plots of the fractional distribution of the different species against temperature show a marked change of slope at around 37--40 degrees C. The effects are essentially reversible over the range 1--45 degrees C and independent of the presence of the spectrin--actin network. The results could be due to temperature-dependent protein--protein associations mediated either by a protein conformational change or by lipid phase segregation. In further experiments, the cholesterol content of the erythrocyte membrane is varied by incubation with lipid vesicles. No significant changes in the rotational diffusion of band 3 are observed following variation of membrane cholesterol/phospholipid mole ratios over the range 0.34--1.66. This is a surprising result in view of the well-known effects of cholesterol on lipid fluidity.
E A Nigg, and
R J Cherry
September 1976,
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E A Nigg, and
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August 1982,
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E A Nigg, and
R J Cherry
January 1992,
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E A Nigg, and
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January 1981,
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E A Nigg, and
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October 1990,
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E A Nigg, and
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January 1992,
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E A Nigg, and
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April 1991,
Biochemistry,
E A Nigg, and
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January 1984,
European biophysics journal : EBJ,
E A Nigg, and
R J Cherry
May 1989,
Biochimica et biophysica acta,
E A Nigg, and
R J Cherry
April 1991,
Biochemistry,
