A comparative and phylogenetic analysis of the alpha-actinin rod domain.
Alpha-actinin is a ubiquitous actin-binding protein, composed of 3 domains; an actin-binding domain and a calcium-binding domain at the termini, connected by a rod domain composed by 1, 2, or 4 spectrin repeats (SRs). To understand how the rod domain has evolved during evolution, we have analyzed and compared the amino acid residue heterogeneity and phylogeny of the SRs of alpha-actinins of vertebrates, invertebrates, fungi, and several protozoa. The repeats of vertebrate alpha-actinins show a high degree of similarity, whereas repeats of invertebrates, fungi, and, in particular, of protozoa are more divergent. In the phylogeny, SR1 of all species were clustered together, independent of the number of repeats in the protein. It was also obvious that the second and last repeat in fungi (SR2) grouped with the fourth and last repeat of vertebrates and invertebrates (SR4). Therefore, the phylogeny implied that the rod domain of the cenancestral alpha-actinin only contained one SR. It was also obvious that SR2 of fungi are related to SR4 of vertebrates and invertebrates, implying that in the second intragenic duplication 2 repeats (i.e., what become SR2 and SR3) were inserted between the initial 2 repeats that become SR1 and SR4.
Virel
Ana
A
Department of Biochemistry, Umeå University, Umeå, Sweden.
Backman
Lars
L
D000185:Actinin / Q000737:chemistry* / Q000145:classification* / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D005656:Fungal Proteins / Q000737:chemistry / Q000145:classification / Q000235:genetics; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D020033:Protein Isoforms / Q000737:chemistry / Q000145:classification / Q000235:genetics; D017433:Protein Structure, Secondary; D015800:Protozoan Proteins / Q000737:chemistry / Q000145:classification / Q000235:genetics; D016415:Sequence Alignment
D005656:Fungal Proteins; D020033:Protein Isoforms; D015800:Protozoan Proteins; D000185:Actinin