G-actin and F-actin levels at different stages of mouse erythroid differentiation.

Monomeric (G-) actin and filamentous (F-) actin levels were determined in Triton X-100 extracts prepared from mouse erythroid cells at various stages of differentiation. G-actin and F-actin were found in the Triton-soluble fraction and in the Triton-insoluble fraction, respectively. G-actin levels in untreated and dimethyl sulfoxide-treated (differentiated) erythroleukemia cells, reticulocytes, and erythrocytes were 48, 33, 2.8, and 0.37 microgram/mg protein, respectively, and F-actin levels were 17, 35, 45, and 59 micrograms/mg protein, respectively. G-actin/F-actin ratios were successively lower in cells representing the more mature stages of development.