ADF/cofilin is not essential but is critically important for actin activities during phagocytosis in Tetrahymena thermophila.

ADF/cofilin is a highly conserved actin-modulating protein. Reorganization of the actin cytoskeleton in vivo through severing and depolymerizing of F-actin by this protein is essential for various cellular events, such as endocytosis, phagocytosis, cytokinesis, and cell migration. We show that in the ciliate Tetrahymena thermophila, the ADF/cofilin homologue Adf73p associates with actin on nascent food vacuoles.

Usual and unusual biochemical properties of ADF/cofilin-like protein Adf73p in ciliate Tetrahymena thermophila.

Actin-depolymerizing factor (ADF)/cofilin is a well-conserved actin-modulating protein, which induces reorganization of the actin cytoskeleton by severing and depolymerizing F-actin. ADF/cofilin also binds to G-actin and inhibits nucleotide exchange, and hence, is supposed to regulate the nucleotide-bound state of the cellular G-actin pool cooperating with profilin, another well-conserved G-actin-binding protein that promotes nucleotide exchange. In this report, we investigated the biochemical properties of the ADF/cofilin-like protein Adf73p from ciliate Tetrahymena thermophila.