Practice question

Cellular cargo movement includes vesicular trafficking but cilia and flagella beating demands distinct high power motors specialized for sliding instead of cargo carrying. Axonemal dynein evolved from cytoplasmic dynein forms large arrays of outer and inner dynein arms repeating every 96 nm along A tubule of axonemal doublet in nine fold symmetric axoneme. Each arm hydrolyzes ATP in AAA1 to AAA4 rings transmitting conformational change through stalk causing sliding of adjacent B tubule toward base at velocities up to 5 microns per second. Because axoneme constrained by radial spokes linking doublets to central pair and nexin dynein regulatory complex crosslinking doublets sliding converted into bending propagated as waves driving fluid propulsion. Cytoplasmic dynein transports vesicles toward minus ends transport toward plus ends performed by kinesin severing done by katanin. Thus major force for cilia and flagella movement originates from axonemal dynein essential for mucociliary clearance reproduction and left right asymmetry establishment during development.