Characterization of Entamoeba histolytica α-actinin

We have cloned, expressed and characterized a α-actinin-like protein of Entamoeba histolytica. Analysis of the primary structure reveals that the essential domains of the α-actinin protein family are conserved: an N-terminus actin-binding domain, a C-terminus calcium-binding domain and a central helical rod domain. However, the rod domain of this Entamoeba protein is considerably shorter than the rod domain in α-actinins of higher organisms.The cloned Entamoeba 63 kDa protein is recognized by conventional α-actinin antibodies as well as binds and cross-links filamentous actin and calcium ions in the same manner as α-actinins. Despite the shorter rod domain this protein has conserved the most important functions of α-actinins. Therefore, it is suggested that this 63 kDa protein is an atypical and ancestral α-actinin.