MOVEMENT OF YEAST CORTICAL ACTIN CYTOSKELETON VISUALIZED IN-VIVO

Fusion proteins between the green fluorescent protein (GFP) and the cy toskeleton proteins Act1p (actin), Sac6p (yeast fimbrin homolog), and Abp1p in budding yeast (Saccharomyces cerevisiae) localize to the cort ical actin patches. The actin fusions could not function as the sole a ctin source in yeast, but fusions between the actin-binding proteins A bp1p and Sac6p complement fully the phenotypes associated with their g ene deletions. Direct observation in vivo reveals that the actin corti cal patches move. Movement of actin patches is constrained to the asym metric distribution of the patches in growing cells, and this movement is greatly reduced when metabolic inhibitors such as sodium azide are added. Fusion protein-labeled patches are normally distributed during the yeast cell cycle and during mating. In vivo observation made poss ible the visualization of actin patches during sporulation as well.