title: Actin capping proteins, CapZ (β-actinin) and tropomodulin in amphioxus striated muscle.
abstract: CapZ (β-actinin) and tropomodulin (Tmod) are capping proteins involved in the maintenance of thin filaments in vertebrate skeletal muscles. In this study, we focused on amphioxus, the most primitive chordate. We searched for CapZ and Tmod genes in the amphioxus genome and determined their primary structures. Amphioxus possess one CapZα gene (CAPZA) and one CapZβ gene (CAPZB), and the transcripts of these genes were found to be 67%-85% identical to those of human CapZ genes. On the other hand, amphioxus contain one Tmod gene (TMOD), and the product of this gene has an identity of approximately 50% with human Tmod genes 1-4. However, helix 2 of amphioxus Tmod, which is involved in protein-binding to tropomyosin, was highly conserved with approximately 74% identity to human Tmod genes. Western blotting indicated the presence of CapZ and Tmod in the striated muscle of amphioxus. These results suggest that unlike most of vertebrates, such as fish, amphibian, bird, and mammal, CapZ from amphioxus striated muscle is derived from two genes CAPZA and CAPZB, and Tmod is derived from one TMOD gene.
authors.affiliation: Department of Biology, Graduate School of Science, Chiba University, Chiba 263-8522, Japan.
authors.forename: Yulong
authors.initials: Y
authors.lastname: Bao
authors.forename: Takei
authors.initials: T
authors.lastname: Kake
authors.forename: Akira
authors.initials: A
authors.lastname: Hanashima
authors.forename: Yui
authors.initials: Y
authors.lastname: Nomiya
authors.forename: Kaoru
authors.initials: K
authors.lastname: Kubokawa
authors.forename: Sumiko
authors.initials: S
authors.lastname: Kimura
mesh_terms: D000185:Actinin / Q000145:classification / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D051347:CapZ Actin Capping Protein / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D043344:Chordata / Q000235:genetics* / Q000378:metabolism; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D014644:Genetic Variation; D006801:Humans; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000378:metabolism*; D010802:Phylogeny; D020033:Protein Isoforms / Q000145:classification / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D051348:Tropomodulin / Q000145:classification / Q000235:genetics* / Q000378:metabolism
chemical_list: D051347:CapZ Actin Capping Protein; D018076:DNA, Complementary; D020033:Protein Isoforms; D051348:Tropomodulin; D000185:Actinin