A Mutation in the Subunit of the Platelet Integrin IIbβ3 Identifies a Novel Region Important for Ligand Binding
An unbiased genetic approach was used to identify a specific amino acid residue in the IIb subunit important for the ligand binding function of the integrin IIbβ. Chemically mutagenized cells were selected by flow cytometry based on their inability to bind the ligand mimetic antibody PAC1 and a ce...
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Veröffentlicht in: | Blood 1999-02, Vol.93 (3), p.918-924 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | An unbiased genetic approach was used to identify a specific amino acid residue in the IIb subunit important for the ligand binding function of the integrin IIbβ. Chemically mutagenized cells were selected by flow cytometry based on their inability to bind the ligand mimetic antibody PAC1 and a cell line containing a single amino acid substitution in IIb at position 224 (D→V) was identified. Although well expressed on the surface of transfected cells, IIbD224Vβ3 as well as IIbD224Aβ3 did not bind IIbβ3-specific ligands or a RGD peptide, a ligand shared in common with vβ3. Insertion of exon 5 of IIb, residues G193-W235, into the backbone of the v subunit did not enable the chimeric receptor to bind IIbβ3-specific ligands. However, the chimeric receptor was still capable of binding to a RGD affinity matrix. IIbD224 is not well conserved among other integrin subunits and is located in a region of significant variability. In addition, amino acid D224 lies within a predicted loop of the recently proposed β-propeller model for integrin subunits and is adjacent to a loop containing amino acid residues previously implicated in receptor function. These data support a role for this region in ligand binding function of the IIbβ3 receptor. |
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ISSN: | 0006-4971 1528-0020 |
DOI: | 10.1182/blood.V93.3.918 |