The genome of the chlorarchiniophyte codes for a protein annotated as an α-actinin-like protein. Analysis of the primary sequence indicate that this protein has the same domain structure as other α-actinins， a N-terminal actin-binding domain and a C-terminal calmodulin-like domain. These two domains are connected by a short rod domain， albeit long enough to form a single spectrin repeat. To analyse the functional properties of this protein， the full-length protein as well as the separate domains were cloned and isolated. Characerisation showed that the protein is capable of cross-linking actin filaments into dense bundles， probably due to dimer formation. Similar to human α-actinin， calcium-binding occurs to the most N-terminal EF-hand motif in the calmodulin-like C-terminal domain. The results indicate that this protein is a proper α-actinin， with all common characteristics of a typical α-actinin.