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The interaction betweena-dystroglycan (a-DG) andb-dystroglycan (b-DG), the two constituent subunits of the adhesion complex dystroglycan, is crucial in maintaining the integrity of the dystrophin–glycoprotein complex. The importance of the a–binterface can be seen in the skeletal muscle of humans affected by severe conditions, such as Duchenne muscular dystrophy, where thea–binteraction can be secondarily weakened or completely lost, causing sarcolemmal instability and muscular necrosis. | Mutagenesis at the a-p interface impairs the cleavage of the dystroglycan precursor Francesca Sciandra1 Manuela Bozzi2 Simona Morlacchi1 3 Antonio Galtieri4 Bruno Giardina1 2 and Andrea Brancaccio1 1 Istituto di Chimica delRiconoscimento Molecolare CNR c o Istituto di Biochimica e Biochimica Clinica Universita Cattolica del Sacro Cuore Rome Italy 2 Istituto di Biochimica e Biochimica Clinica Universita Cattolica delSacro Cuore Rome Italy 3 Dipartimento di Biologia Animale ed Ecologia Marina Universita degli Studi di Messina Italy 4 Dipartimento di Chimica Organica e Biologica University di Messina Italy Keywords alanine scanning dystroglycan dystroglycan precursor laminin binding post-translational processing Correspondence A. Brancaccio Istituto di Chimica del Riconoscimento Molecolare CNR c o Istituto di Biochimica e Biochimica Clinica Universita Cattolica delSacro Cuore L.go F. Vito 1 00168 Rome Italy Fax 39 6 3053598 Tel 39 6 3057612 E-mail andrea.brancaccio@icrm.cnr.it These two authors contributed equally to this work Received 29 April2009 revised 10 June 2009 accepted 3 July 2009 doi 10.1111 j.1742-4658.2009.07196.x The interaction between a-dystroglycan a-DG and b-dystroglycan b-DG the two constituent subunits of the adhesion complex dystroglycan is crucial in maintaining the integrity of the dystrophin-glycoprotein complex. The importance of the a-b interface can be seen in the skeletal muscle of humans affected by severe conditions such as Duchenne muscular dystrophy where the a-b interaction can be secondarily weakened or completely lost causing sarcolemmal instability and muscular necrosis. The reciprocal binding epitopes of the two subunits reside within the C-terminus of a-DG and the ectodomain of b-DG. As no ultimate structural data are yet available on the a-b interface site-directed mutagenesis was used to identify which specific amino acids are involved in the interaction. A previous alanine-scanning analysis of the recombinant b-DG ectodomain .
