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Diameter of flagellum internal channel

Value	2 nm
Organism	Bacteria Salmonella typhimurium
Reference	Yonekura K, Maki-Yonekura S, Namba K. Complete atomic model of the bacterial flagellar filament by electron cryomicroscopy. Nature. 2003 Aug 7 424(6949):643-50PubMed ID12904785
Method	Flagellin was isolated from S. typhimurium strain SJW1655 and the R-type straight flagellar filament. Electron cryomicroscopy: Images of frozen hydrated filaments were taken with a JEOL JEM-3000SFF electron microscope with its field emission gun operated at 300 kV and the specimen temperature of 4 K.
Comments	During the growth of the filament, a large number of flagellin molecules, together with a small number of hook-associated proteins—HAP1, HAP2 and HAP3—are synthesized in the cell and are selectively translocated by the flagellar type III protein export system into the long, narrow central channel of the flagellum (30, 31), through which they are transported to the distal end. The diameter of the central channel was previously estimated to be about 30 Å from the density maps of the filaments at around 10 Å resolution (ref 14, 15), but in the atomic model it is only about 20 Å (Fig. 6d).
Entered by	Uri M
ID	104903