Papa I, Méjean C, Lebart M C, Astier C, Roustan C, Benyamin Y, Alvarez C, Verrez-Bagnis V, Fleurence J
UPR 9008 (CNRS), U. 249 (INSERM), Laboratoire de Recherche sur la Motilité Cellulaire, (EPHE), Université de Montpellier I, France.
Comp Biochem Physiol B Biochem Mol Biol. 1995 Oct;112(2):271-82. doi: 10.1016/0305-0491(95)00095-x.
Fish alpha-actinin purified from sea-trout and bass white muscle by means of two different extraction procedures was used to investigate the eventual presence of different muscle isoforms in Z-disks. These fish alpha-actinins have the same apparent molecular weight (100 kDa) and the same isoelectric point (pI = 5.6), and also have a total antigenic identity towards anti-bass and anti-chicken alpha-actinin antibodies, suggesting a single molecular species. The role of fish alpha-actinin as an anchorage site for thin actin filaments and elastic titin filaments in Z-bands was studied. Despite conservation of the actin-binding site, fish alpha-actinin has a better actin-binding ability (kD = 0.3 microM) than chicken smooth muscle alpha-actinin (kD = 1.6 microM). Several other structural and functional characteristics of fish alpha-actinin were also studied: conservation of sequence and domain structure, the role of divalent ions (Ca2+, Mg2+) and the dielectric constant of the medium in alpha-actinin-actin interaction. Although the reason for fish white muscle alpha-actinin's close affinity to actin was not clearly established, our results suggested that the physicochemical environment of the Z-filaments in Z-disks might be crucial.
