Effects of Profilin and Profilin-Actin Complexes on Lamellipodia

Cao et al., J. Cell Biol. 117:1023-1029 (1992)

Profilin is first identified as an actin monomer sequestration protein, but is later found to allow or even promote the assembly of actin monomers to the barbed end of actin filaments. To investigate the cellular function of profilin, cultured Normal Rat Kidney epithelial cells were microinjected with a large amount of profilin or profilin-actin complexes.

Microinjection of Excess Profilin Causes Shrinkage of Lamellipodia

The cell to the left was microinjected with a high concentrations of profilin. Its lamellipodia show a reduced size but nevertheless remain active. Recording time, 5 min.

Microinjection of Excess Profilin-Actin Complexes Causes Expansion of Lamellipodia

The cell to the left was microinjected with a high concentration of profilin-actin high affinity complexes. Its lamellipodia show a striking increase in size and very active ruffling activities. Recording time, 3 min.