Localization of the dystrophin binding site at the carboxyl terminus of beta-dystroglycan.
Alpha- and beta-dystroglycan form a heteromeric transmembrane complex linking the extracellular matrix to the cytoskeleton. In muscle beta-dystroglycan interacts with dystrophin on the inside of the cell and with alpha-dystroglycan, which binds the extracellular matrix protein laminin, on the outside. Dystroglycan is expressed not only in muscle but also in other tissues. We cloned beta-dystroglycan from rabbit brain by RT-PCR and expressed deletion mutants of the beta-dystroglycan cytoplasmic domain as GST-fusion proteins. We identified the dystrophin binding region on beta-dystroglycan by protein overlay and co-precipitation assays with skeletal muscle dystrophin and recombinant apo-dystrophin I. We demonstrate that the beta-dystroglycan carboxyl terminus interacts with dystrophin and that the binding site is restricted to the last 20 amino acids. Our data also suggest that the region adjacent to the beta-dystroglycan transmembrane domain might modulate beta-dystroglycan-dystrophin interaction.
Rosa
G
G
Laboratorio di Biologia Cellulare, Istituto Superiore di Sanita, Rome, Italy.
Ceccarini
M
M
Cavaldesi
M
M
Zini
M
M
Petrucci
T C
TC
D000818:Animals; D001059:Apoproteins / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites; D001921:Brain / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D017931:DNA Primers; D049030:Dystroglycans; D016189:Dystrophin / Q000378:metabolism*; D005982:Glutathione Transferase / Q000096:biosynthesis; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000378:metabolism; D016296:Mutagenesis; D016133:Polymerase Chain Reaction; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D017384:Sequence Deletion
D001059:Apoproteins; D003598:Cytoskeletal Proteins; D017931:DNA Primers; D016189:Dystrophin; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D049030:Dystroglycans; D005982:Glutathione Transferase