Adhesion-dependent tyrosine phosphorylation of (beta)-dystroglycan regulates its interaction with utrophin.

Many cell adhesion-dependent processes are regulated by tyrosine phosphorylation. In order to investigate the role of tyrosine phosphorylation of the utrophin-dystroglycan complex we treated suspended or adherent cultures of HeLa cells with peroxyvanadate and immunoprecipitated (beta)-dystroglycan and utrophin from cell extracts. Western blotting of (&bgr;)-dystroglycan and utrophin revealed adhesion- and ...
peroxyvanadate-dependent mobility shifts which were recognised by anti-phospho-tyrosine antibodies. Using maltose binding protein fusion constructs to the carboxy-terminal domains of utrophin we were able to demonstrate specific interactions between the WW, EF and ZZ domains of utrophin and (beta)-dystroglycan by co-immunoprecipitation with endogenous (beta)-dystroglycan. In extracts from cells treated with peroxyvanadate, where endogenous (beta)-dystroglycan was tyrosine phosphorylated, (beta)-dystroglycan was no longer co-immunoprecipitated with utrophin fusion constructs. Peptide 'SPOTs' assays confirmed that tyrosine phosphorylation of (beta)-dystroglycan regulated the binding of utrophin. The phosphorylated tyrosine was identified as Y(892) in the (beta)-dystroglycan WW domain binding motif PPxY thus demonstrating the physiological regulation of the (beta)-dystroglycan/utrophin interaction by adhesion-dependent tyrosine phosphorylation.
Mesh Terms:
Amino Acid Motifs, Amino Acid Sequence, Binding Sites, Cell Adhesion, Cell Membrane, Cytoskeletal Proteins, Dystroglycans, Hela Cells, Humans, Membrane Glycoproteins, Membrane Proteins, Molecular Sequence Data, Phosphorylation, Protein Structure, Tertiary, Tyrosine, Utrophin, Vanadates
J. Cell. Sci.
Date: May. 01, 2000
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