Laminins are a group of extracellular-matrix proteins important in development and disease. They are heterotrimers, and specific domains in the different chains have specialized functions. The G domain of the α5 chain has now been produced in transfected mammalian cells as single modules and two tandem arrays, α5LG1–3 and α5LG4–5 (LG is laminin G domain-like). Using these fragments we produced specific polyclonal antibodies functional in immunoblotting and immunofluorescence studies and in solid-phase assays. Both α5LG tandem arrays had physiologically relevant affinities for sulphated ligands such as heparin and sulphatides. Cells adhered to these fragments and acquired a spread morphology when plated on α5LG1–3. Binding of integrins α3β1 and α6β1 was localized to the α5LG1–3 modules, and α-dystroglycan binding was localized to the α5LG4–5 modules, thus locating these activities to different LG modules within the laminin α5 G domain. However, both these activities were of relatively low affinity, indicating that integrin-mediated cell adhesion to the laminin 10/11 α5G domain depends on contributions from the other chains of the heterotrimer and that high-affinity α-dystroglycan binding could be dependent on specific Ca2+-ion-co-ordinating amino acids absent from α5LG4–5.
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April 2003
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Research Article|
April 15 2003
beta1 Integrin and alpha-dystroglycan binding sites are localized to different laminin-G-domain-like (LG) modules within the laminin alpha5 chain G domain
Hao YU;
Hao YU
Department of Cell and Molecular Biology, Section of Cell and Developmental Biology, BMC, B12, Lund University, SE-221 84 Lund, Sweden
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Jan F. TALTS
Jan F. TALTS
1
Department of Cell and Molecular Biology, Section of Cell and Developmental Biology, BMC, B12, Lund University, SE-221 84 Lund, Sweden
1To whom correspondence should be addressed (e-mail jan.talts@medkem.lu.se).
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Publisher: Portland Press Ltd
Received:
September 26 2002
Revision Received:
January 03 2003
Accepted:
January 08 2003
Accepted Manuscript online:
January 08 2003
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London ©2003
2003
Biochem J (2003) 371 (2): 289–299.
Article history
Received:
September 26 2002
Revision Received:
January 03 2003
Accepted:
January 08 2003
Accepted Manuscript online:
January 08 2003
Citation
Hao YU, Jan F. TALTS; beta1 Integrin and alpha-dystroglycan binding sites are localized to different laminin-G-domain-like (LG) modules within the laminin alpha5 chain G domain. Biochem J 15 April 2003; 371 (2): 289–299. doi: https://doi.org/10.1042/bj20021500
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