Skeletal myoblasts utilize a novel beta 1-series integrin and not alpha 6 beta 1 for binding to the E8 and T8 fragments of laminin.
The E8 fragment of laminin stimulates myoblast attachment and locomotion. Myoblast attachment to laminin/E8 was blocked by anti-integrin antibodies against beta 1-chains but not by antibodies against alpha 6-chains. By contrast, other cell lines (e.g. B16, HT1080, P19, F9, Pys2, 3T3, and 3T6) were blocked both by anti-beta 1 and anti-alpha 6. All cells tested also bound to approximately 125-kDa C-terminal fragments of E8 (T8 and T8'). Immunoprecipitation of surface-iodinated myoblasts revealed beta 1-, alpha 3-, and alpha 5-integrin chains and a novel chain that co-precipitated with anti-beta 1 antibodies running at approximately 95 kDa (reduced). I125-alpha 6 beta 1 was immunoprecipitated from cells whose attachment to E8 was blocked by anti-alpha 6 antibodies. By contrast, little alpha 6 beta 1 could be immunoprecipitated from myoblasts. beta 1-Integrin and the novel alpha-chain (alpha'), Mr approximately 120,000/approximately 95.000 (nonreduced/reduced), from myoblast lysates were retained during affinity chromatography on Engelbreth-Holm-Swarm-laminin affinity columns. beta 1, alpha 1, and the novel alpha' were retained from Rugli cell lysates on Engelbreth-Holm-Swarm-laminin columns. alpha 3 was not bound. When E8 was used as affinity matrix, only beta 1 and alpha' were retained. The N-terminal sequence of Rugli alpha' was homologous to alpha-chains of beta 1-series integrins and was most similar to alpha 6 (9 identical residues out of 14). However, there were distinctive differences; in particular, 2 residues were deleted in comparison with alpha 6.
von der Mark
H
H
Max Planck Society Clinical Research Group for Rheumatology, University of Erlangen/Nürnberg, Germany.
Dürr
J
J
Sonnenberg
A
A
von der Mark
K
K
Deutzmann
R
R
Goodman
S L
SL
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D000936:Antigen-Antibody Complex; D001665:Binding Sites; D002448:Cell Adhesion; D002460:Cell Line; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D016023:Integrins / Q000276:immunology / Q000378:metabolism*; D007797:Laminin / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009132:Muscles / Q000502:physiology*; D010446:Peptide Fragments / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid
D000906:Antibodies; D000936:Antigen-Antibody Complex; D016023:Integrins; D007797:Laminin; D010446:Peptide Fragments