"We used the fluorescently labeled hook to demonstrate that FlgE is the hook structural protein"

"FliK regulated hook length"

"FlhO and FlhP, and the putative hook cap, FlgD, were required for hook assembly"

"All mutants defective in hook completion resulted in homogeneously reduced sigma(D)-dependent gene expression due to the action of the anti-sigma factor FlgM"

"FlgM is also secreted in the Gram-positive bacterium Bacillus subtilis and is degraded extracellularly by the proteases Epr and WprA"

"the structural genes required for the flagellar hook-basal body are required for robust activation of sigma(D)-dependent gene expression and efficient secretion of FlgM"

"the substrate specificity switch regulator FliK"

"FlgM secretion is strongly enhanced by, but does not strictly require, hook-basal body completion and instead demands a minimal subset of flagellar proteins that includes...the substrate specificity switch regulator FliK"