title: Conformational changes in CD45 upon monoclonal antibody crosslinking.
abstract: The CD45 protein tyrosine phosphatase is expressed in different isoforms that result from alternative splicing of three exons (A, B, and C) encoding regions near the N-terminus of the extracellular part of the molecule. We describe here a novel epitope on the N-terminal end of CD45 that is recognized by the MAb BL-TSub/2. Crossblocking studies showed that BL-TSub/2 and UCHL1 (CD45RO) binding sites are partially overlapping. However, in marked contrast to the CD45RO epitope, protease treatment of cells strongly diminished BL-TSub/2 binding. Similar to the UCHL1 epitope, the BL-TSub/2 binding site involves carbohydrate moieties, since neuraminidase treatment abrogated the reactivity of the MAb. Markedly, preincubation of cells with both CD45 common and CD45RA MAb induced a pronounced increase of BL-TSub/2 binding. This latter finding suggests that crosslinking of the CD45 molecule leads to conformational changes that could influence association of the molecule with putative ligands.
authors.affiliation: Central Laboratory of the Netherlands, Red Cross Blood Transfusion Service, University of Amsterdam.
authors.forename: D
authors.initials: D
authors.lastname: Hamann
authors.forename: W
authors.initials: W
authors.lastname: Eichler
authors.forename: H
authors.initials: H
authors.lastname: Fiebig
authors.forename: R A
authors.initials: RA
authors.lastname: van Lier
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D001666:Binding Sites, Antibody; D003432:Cross-Linking Reagents; D006801:Humans; D017493:Leukocyte Common Antigens / Q000737:chemistry* / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C
chemical_list: D000911:Antibodies, Monoclonal; D003432:Cross-Linking Reagents; D017493:Leukocyte Common Antigens