title: Crystal structure of the M-fragment of alpha-catenin: implications for modulation of cell adhesion.
abstract: The cytoskeletal protein alpha-catenin, which shares structural similarity with vinculin, is required for cadherin-mediated cell adhesion, and functions to modulate cell adhesive strength and to link the cadherins to the actin-based cytoskeleton. Here we describe the crystal structure of a region of alpha-catenin (residues 377-633) termed the M-fragment. The M-fragment is composed of a tandem repeat of two antiparallel four-helix bundles of virtually identical architectures that are related in structure to the dimerization domain of alpha-catenin and the tail region of vinculin. These results suggest that alpha-catenin is composed of repeating antiparallel helical domains. The region of alpha-catenin previously defined as an adhesion modulation domain corresponds to the C-terminal four-helix bundle of the M-fragment, and in the crystal lattice these domains exist as dimers. Evidence for dimerization of the M-fragment of alpha-catenin in solution was detected by chemical cross-linking experiments. The tendency of the adhesion modulation domain to form dimers may explain its biological activity of promoting cell-cell adhesiveness by inducing lateral dimerization of the associated cadherin molecule.
authors.affiliation: Section of Structural Biology, Institute of Cancer Research, Chester Beatty Laboratories, 237 Fulham Road, London SW3 6JB, UK.
authors.forename: J
authors.initials: J
authors.lastname: Yang
authors.forename: P
authors.initials: P
authors.lastname: Dokurno
authors.forename: N K
authors.initials: NK
authors.lastname: Tonks
authors.forename: D
authors.initials: D
authors.lastname: Barford
mesh_terms: D000595:Amino Acid Sequence; D002448:Cell Adhesion / Q000502:physiology*; D018360:Crystallography, X-Ray; D003598:Cytoskeletal Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000502:physiology*; D019281:Dimerization; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification / Q000502:physiology*; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D020449:Repetitive Sequences, Amino Acid; D017386:Sequence Homology, Amino Acid; D016596:Vinculin / Q000737:chemistry; D051178:alpha Catenin
chemical_list: C495273:CTNNA1 protein, human; D003598:Cytoskeletal Proteins; D010446:Peptide Fragments; D011994:Recombinant Proteins; D051178:alpha Catenin; D016596:Vinculin