% IMPORTANT: The following is UTF-8 encoded. This means that in the presence % of non-ASCII characters, it will not work with BibTeX 0.99 or older. % Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or % “biber”. @ARTICLE{Pagani:844002, author = {Pagani, Guilia and Pereira, Joana P. V. and Stoldt, Volker R. and Beck, Andreas and Scharf, Rüdiger E. and Gohlke, Holger}, title = {{T}he human platelet antigen-1b variant of $\alpha$$_{{II}b}$β$_{3}$ allosterically shifts the dynamic conformational equilibrium of this integrin toward the active state}, journal = {The journal of biological chemistry}, volume = {293}, issn = {0021-9258}, address = {Bethesda, Md.}, publisher = {Soc.}, reportid = {FZJ-2018-01518}, pages = {4830-4844}, year = {2018}, abstract = {Integrins are heterodimeric cell-adhesion receptors comprising α and β subunits. The human platelet antigen-1 (HPA-1) polymorphism in αIIbβ3 arises from a Leu→Pro exchange at residue 33 in the genu of the β3 subunit, resulting in Leu-33 (HPA-1a) or Pro-33 (HPA-1b) isoforms. Although clinical investigations have provided conflicting results, some studies have suggested that Pro-33 platelets exhibit increased thrombogenicity. Under flow-dynamic conditions, the Pro-33 variant displays prothrombotic properties, characterized by increased platelet adhesion, aggregate/thrombus formation, and outside-in signaling. However, the molecular events underlying this prothrombotic phenotype have remained elusive. As residue 33 is located > 80 Å away from extracellular binding sites or transmembrane domains, we hypothesized that the Leu→Pro exchange allosterically shifts the dynamic conformational equilibrium of αIIbβ3 toward an active state. Multiple microsecond-long, all-atom molecular dynamics simulations of the ectodomain of the Leu-33 and Pro-33 isoforms provided evidence that the Leu→Pro exchange weakens interdomain interactions at the genu and alters the structural dynamics of the integrin to a more unbent and splayed state. Using FRET analysis of fluorescent proteins fused with αIIbβ3 in transfected HEK293 cells, we found that the Pro-33 variant in its resting state displays a lower energy transfer than the Leu-33 isoform. This finding indicated a larger spatial separation of the cytoplasmic tails in the Pro-33 variant. Together, our results indicate that the Leu→Pro exchange allosterically shifts the dynamic conformational equilibrium of αIIbβ3 to a structural state closer to the active one, promoting the fully active state and fostering the prothrombotic phenotype of Pro-33 platelets.}, cin = {JSC / ICS-6}, ddc = {570}, cid = {I:(DE-Juel1)JSC-20090406 / I:(DE-Juel1)ICS-6-20110106}, pnm = {511 - Computational Science and Mathematical Methods (POF3-511)}, pid = {G:(DE-HGF)POF3-511}, typ = {PUB:(DE-HGF)16}, pubmed = {pmid:29462793}, UT = {WOS:000428848300023}, doi = {10.1074/jbc.RA118.002149}, url = {https://juser.fz-juelich.de/record/844002}, }