Permissive transmembrane helix heterodimerization is required for the expression of a functional integrin
| العنوان: | Permissive transmembrane helix heterodimerization is required for the expression of a functional integrin |
|---|---|
| المؤلفون: | Chi Hang Wong, Suet-Mien Tan, Ardcharaporn Vararattanavech, Man-Li Tang, S. K. Alex Law, Jaume Torres, Hoi-Yeung Li |
| المصدر: | Biochemical Journal. 410:495-502 |
| بيانات النشر: | Portland Press Ltd., 2008. |
| سنة النشر: | 2008 |
| مصطلحات موضوعية: | Integrins, DNA, Complementary, Protein Conformation, Integrin, Biochemistry, CD49c, Cell Line, Collagen receptor, Fluorescence Resonance Energy Transfer, Humans, Immunoprecipitation, Molecular Biology, biology, Membrane Proteins, Cell Biology, Flow Cytometry, Molecular biology, Cell biology, Transmembrane domain, Förster resonance energy transfer, Integrin alpha M, biology.protein, Integrin, beta 6, Dimerization, ITGA6, Plasmids, Protein Binding |
| الوصف: | The current paradigm is that integrin is activated via inside-out signalling when its cytoplasmic tails and TMs (transmembrane helices) are separated by specific cytosolic protein(s). Perturbations of the helical interface between the alpha- and beta-TMs of an integrin, as a result of mutations, affect its function. Previous studies have shown the requirement for specific pairing between integrin subunits by ectodomain-exchange analyses. It remains unknown whether permissive alpha/beta-TM pairing of an integrin is also required for pairing specificity and the expression of a functionally regulated receptor. We performed scanning replacement of integrin beta2-TM with a TM of other integrin beta-subunits. With the exception of beta4 substitution, others presented beta2-integrins with modified phenotypes, either in their expression or ligand-binding properties. Subsequently, we adopted alphaLbeta2 for follow-on experiments because its conformation and affinity-state transitions have been well defined as compared with other members of the beta2-integrins. Replacement of beta2- with beta3-TM generated a chimaeric alphaLbeta2 of an intermediate affinity that adhered to ICAM-1 (intercellular adhesion molecule 1) but not to ICAM-3 constitutively. Replacing alphaL-TM with alphaIIb-TM, forming a natural alphaIIb/beta3-TM pair, reversed the phenotype of the chimaera to that of wild-type alphaLbeta2. Interestingly, the replacement of alphaLbeta2- with beta3-TM showed neither an extended conformation nor the separation of its cytoplasmic tails, which are well-reported hallmarks of an activated alphaLbeta2, as determined by reporter mAb (monoclonal antibody) KIM127 reactivity and FRET (fluorescence resonance energy transfer) measurements respectively. Collectively, our results suggest that TM pairing specificity is required for the expression of a functionally regulated integrin. |
| تدمد: | 1470-8728 0264-6021 |
| الوصول الحر: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::fe094b4c56a56a79ff077e2820345ac8Test https://doi.org/10.1042/bj20071218Test |
| رقم الانضمام: | edsair.doi.dedup.....fe094b4c56a56a79ff077e2820345ac8 |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 14708728 02646021 |
|---|