Localisation of a novel adhesion blocking epitope on the human beta 1 integrin chain.
Members of the beta 1 integrin family mediate cellular adherence to a wide range of extracellular and cell surface associated ligands. Conformational changes have been shown to be associated with integrin activation and ligand binding. Some studies suggest that there may be a restricted region of the beta 1 integrin that serves as the target for regulatory antibodies which can inhibit or stimulate integrin function. Here we identify an inhibitory epitope that is located at a distinct sight from that suggested for other inhibitory antibodies. Three different adhesion blocking antibodies, JB1A, C30B, and D11B bind to a peptide corresponding to residues 82-87 of the mature beta 1 chain. Mn++ inhibited the binding of JB1A to purified beta 1 integrin. In contrast the binding of several other antibodies to beta 1 were not influenced by these conditions. JB1A binding to purified peptide was also inhibited by Mn++ suggesting that it related to interference with the antibody function rather than a cation dependent change in the epitope. Our data 1) directly demonstrates the peptide sequence recognised by three adhesion blocking antibodies to the human beta 1 integrin chain 2) identifies a novel epitope located at residues 82-87, distinct from that of previously described regulatory epitopes 3) characterises a Mn++ sensitive antibody integrin interaction. Collectively, these results indicate the existence of multiple regulatory sites on the beta 1 integrin molecule.
Department of Internal Medicine, University of Manitoba, Canada.
H
H
Ni
J A
JA
Wilkins
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000276:immunology* / Q000494:pharmacology; D000918:Antibody Specificity; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D003001:Cloning, Molecular; D018604:Epitope Mapping; D015723:Gene Library; D006801:Humans; D019012:Integrin beta1 / Q000032:analysis* / Q000235:genetics* / Q000276:immunology; D019169:Jurkat Cells / Q000737:chemistry / Q000166:cytology / Q000502:physiology; D008274:Magnesium / Q000494:pharmacology; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000276:immunology
D000911:Antibodies, Monoclonal; D019012:Integrin beta1; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D008274:Magnesium