Changes in the composition of plasma membrane proteins during differentiation of embryonic chick erythroid cell.

Erythroid cells which are homogeneous with regard to stage of maturation are naturally available from the circulation of chick embryos at various times of development. This provides a convenient system for examining the changes in plasma membrane protein composition during red cell maturation. Plasma membranes are isolated from chick embryonic erythroid cells at various stages of maturation. Extensive characterization of the isolated membranes show that they are pure and their proteins undegraded. Analyses by sodium dodecyl sulfate/polyacrylamide gel electrophoresis show that both qualitative and quantitative changes occur in membrane protein composition during the early stage of erythroid differentiation. Specific proteins of red cell membrane such as "spectrin" and band three proteins are present in low levels in early erythroblasts but increase in their relative amounts with maturation. A steady-state membrane protein composition seems to be established by the late polychromatophilic erythroblast stage.