The previously unknown structure of the inhibitory platelet receptor, G6b-B has now been solved by Peak Proteins in complex with a glycan ligand. This surprisingly revealed a “head to tail” dimer around the glycan ligand with implications for how G6b-B signals to the intracellular environment.
Platelets are highly reactive anucleated cells, produced in the bone marrow, spleen and lungs by megakaryocytes, which circulate in the blood stream and form plugs to stop bleeding when they encounter a damaged blood vessel. Their activation is tightly regulated to avoid hyperactivity, which could occlude blood vessels. G6b-B is a key inhibitory cell surface receptor that is highly expressed on megakaryocytes and platelets. The molecular interactions that enable this inhibitory effect have previously been unknown, but are now revealed in this landmark study which can be viewed here.
The collaborative study was led by Professor Yotis Senis from the University of Birmingham, UK. Peak Proteins’ role was to determine the crystal structure of the extracellular portion when complexed to a glycan ligand. Multiple challenges were overcome including the simplification of the attached oligosaccharide side chains to allow the protein to crystallise, by the engineering and production of different mutant proteins. Further improvements involved co-crystallisation with an antibody Fab fragment and substantial crystallisation optimisation. Finally, crystals that diffracted well were obtained and data collected at the Diamond Light Source Synchrotron facility in Oxford. The G6b-B-Fab structure was solved by molecular replacement methods and the information has been used in a patent filing by the university.
Professor Senis said. ‘Having personally no prior experience of crystallography, Peak Proteins came highly recommended by leading academics in the field. They were highly approachable, experienced and professional, and an excellent rapport was quickly established, keeping my team and I up-to-date on the latest findings, obstacles and solutions. They persevered from start-to-finish, achieving our objective more efficiently and economically than would have been possible otherwise. Money well spent!’
Have a look at our protein crystallography and structure determination services page for more information.