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Epitope mapping by screening of phage display libraries of a monoclonal antibody directed against the receptor binding domain of human α2‐macroglobulin
Author(s) -
Birkenmeier Gerd,
Osman Awad A,
Kopperschläger Gerhard
Publication year - 1997
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(97)01201-5
Subject(s) - epitope , monoclonal antibody , phage display , microbiology and biotechnology , peptide , epitope mapping , peptide library , chemistry , antibody , linear epitope , peptide sequence , receptor , biochemistry , biology , genetics , gene
The human proteinase inhibitor, α2‐macroglobulin (α2‐M), inhibits a large number of proteinases. α2‐M‐proteinase complexes are rapidly cleared from the circulation by binding to a cellular receptor (α2‐M‐R/LRP) via the receptor binding domain (RBD) which is made up of a 20 kDa C‐terminal stretch of the 180 kDa monomer of the inhibitor. A monoclonal antibody (mab α‐1) has been described which reacts with the receptor‐recognizable form of the inhibitor, the so called transformed α2‐M (α2‐Mt). By screening of a phage display library an epitope in the RBD of the inhibitor was identified that reacts with mab α‐1. Out of 25 phage clones a heptapeptide sequence (S‐x 1 ‐x 2 ‐D‐x 3 ‐x 4 ‐K) was obtained containing identical amino acids in three positions. A consensus peptide (S‐R‐S‐D‐P‐P‐K) was synthesized and found to displace α2‐Mt from binding to mab α‐1 and to receptor. The specificity of competition was demonstrated by a reversed peptide and a control antibody. By structural comparison it was found that the consensus heptapeptide mimics a discontinuous conformationally constrained epitope present in the RBD of the inhibitor. This is the first report describing the detection of discontinuous epitopes by phage display using a short linear peptide.