Tropomodulin/tropomyosin interactions regulate actin pointed end dynamics.
Dynamics of the slow-growing (pointed) end of the actin filament is regulated by tropomodulins, a family of capping proteins that require tropomyosin for optimal function. Tropomodulin is an elongated molecule with a molecular mass of about 40 kDa, containing the Tm-independent actin-binding site at the C-terminus. The highly disordered N-terminal half of tropomodulin contains two Tm-binding sites and a Tm-dependent actin-binding site. There are many Tm isoforms whose distribution varies in different tissues and cell compartments and changes during development of these tissues. Tropomyosin/tropomodulin interactions are isoform specific. Differences in Tm affinity for the two binding sites in Tmod may regulate its correct positioning at the pointed end as well as effectiveness of capping actin filament. The regulation of tropomodulin binding may have significant consequences for local cytoskeletal formation and filament dynamics in cells.
Kostyukova
Alla S
AS
Department of Neuroscience and Cell Biology, Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ 08854, USA. kostyuas@umdnj.edu
D000199:Actins / Q000737:chemistry*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D020033:Protein Isoforms; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D051348:Tropomodulin / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D014335:Tropomyosin / Q000737:chemistry / Q000502:physiology*
D000199:Actins; D020033:Protein Isoforms; C495829:TMOD1 protein, human; D051348:Tropomodulin; D014335:Tropomyosin