A two-amino acid insertion in the Cys146- Cys167 loop of the alphaIIb subunit is associated with a variant of Glanzmann thrombasthenia. Critical role of Asp163 in ligand binding.
Open Access
- 15 September 1998
- journal article
- case report
- Published by American Society for Clinical Investigation in JCI Insight
- Vol. 102 (6), 1183-1192
- https://doi.org/10.1172/jci3206
Abstract
The ligand binding site(s) of the alpha subunit of integrin alphaIIb beta3 (GPIIb-IIIa), a prototypic non-I domain integrin, remains elusive. In this study, we have characterized a Japanese variant of Glanzmann thrombasthenia, KO, whose platelets express normal amounts of alphaIIb beta3. KO platelets failed to bind the activation-independent ligand-mimetic mAb OP-G2 and did not bind fibrinogen or the activation-dependent ligand-mimetic mAb PAC-1 following activation of alphaIIb beta3 under any condition examined. Sequence analysis of PCR fragments derived from KO platelet mRNA revealed a 6-bp insertion leading to a 2-amino-acid insertion (Arg-Thr) between residues 160 and 161 of the alphaIIb subunit. Introduction of the insertion into wild-type recombinant alphaIIb beta3 expressed in 293 cells led to the normal expression of alphaIIb beta3 having the defect in ligand binding function. The insertion is located within the small loop (Cys146-Cys167) in the third NH2-terminal repeat of the alphaIIb subunit. Alanine substitution of each of the oxygenated residues within the loop (Thr150, Ser152, Glu157, Asp159, Ser161, and Asp163) did not significantly affect expression of alphaIIbbeta3, and only Asp163AlaalphaIIb beta3 abolished the ligand binding function. In addition, Asp163AlaalphaIIb beta3 as well as KO mutant alphaIIb beta3 constitutively expressed the PMI-1 epitope. Our present data suggest that Asp163 of the alphaIIb subunit is one of the critical residues for ligand binding.Keywords
This publication has 50 references indexed in Scilit:
- Cell adhesion in vascular biology. New insights into integrin-ligand interaction.JCI Insight, 1997
- Platelet GPIIb/IIIa antagonists: the first anti-integrin receptor therapeutics.JCI Insight, 1997
- Molecular Requirements for Assembly and Function of a Minimized Human Integrin αIIbβ3Journal of Biological Chemistry, 1996
- The Amino-terminal One-third of αIIb Defines the Ligand Recognition Specificity of Integrin αIIbβ3Published by Elsevier BV ,1996
- Molecular basis of CD36 deficiency. Evidence that a 478C-->T substitution (proline90-->serine) in CD36 cDNA accounts for CD36 deficiency.JCI Insight, 1995
- Ligand and cation binding are dual functions of a discrete segment of the integrin β3 subunit: Cation displacement is involved in ligand bindingCell, 1994
- Demonstration of a marked reduction in the amount of GPIIb in most type II patients with Glanzmann's thrombastheniaBritish Journal of Haematology, 1994
- A new variant of Glanzmann's thrombasthenia (Strasbourg I). Platelets with functionally defective glycoprotein IIb-IIIa complexes and a glycoprotein IIIa 214Arg----214Trp mutation.JCI Insight, 1992
- Integrins: Versatility, modulation, and signaling in cell adhesionCell, 1992
- Integrins.JCI Insight, 1991