Clonal selection by fluorescence redistribution after photobleaching (FRAP)--a "fast" lateral mobility fibroblast mutant (E7G1).

Fluorescence redistribution after photobleaching (FRAP) was utilized to select a "fast" lateral mobility clone from Kirsten murine sarcoma virus-transformed 3T3 (KMSV-3T3) fibroblasts. The clone, E7G1, demonstrated a lateral mobility for membrane wheat germ agglutinin (WGA) and succinylated concanavalin A (sCon A) receptors of (2.1 +/- 1.6) X 10(-9) cm2/s and (2.7 +/- 2.3) X 10(-9) cm2/s, respectively. These mobilities were approximately equivalent to phospholipid mobility (2.8 +/- 1.9 X 10(-9) cm2/s). The fast mobility phenotype is observed when the cells are unattached and spherical. Upon attachment, the mobility decreases to (0.19 +/- 0.19) X 10(-9) cm2/s. In addition, the ability of Con A to initiate global modulation was completely lost in spread as well as spherical cells in the E7G1 fast mobility clone. A comparison of F-actin patterns between untransformed Balb/c fibroblasts and the E7G1-transformed line suggests a correlation between well-developed stress fiber assemblies and the ability to induce global modulation. The fast mobility clone was stable for at least 23 passages.