Novel actin-like protein (NAP) is a highly divergent actin expressed in Chlamydomonas. With its low sequence similarity, it is uncertain whether NAP can polymerize into filaments. Here I assessed it by ectopically expressing enhanced green fluorescent protein-tagged NAP (EGFP-NAP) in cultured cells. EGFP-NAP was excluded from stress fibres but partially co-localized with endogenous actin in the cell periphery. In fluorescence recovery after photobleaching experiment, turnover rate of EGFP-NAP was similar to the estimated diffusion rate of monomeric actin. Therefore, EGFP-NAP likely accumulates by diffusion. These findings suggest that NAP has extremely poor ability to polymerize. (C) 2011 Elsevier Inc. All rights reserved.