Effects of AMPPNP and vanadate on the mechanochemical crossbridge cycle in flagella

The non-hydrolysable ATP analogue, beta,gamma-imido-adenosine-5'-triphosphate (AMPPNP, adenylilimidodiphosphate) does not reduce the stiffness of demembranated sea urchin sperm flagella measured in the rigor state in the absence of MgATP2- and does not cause relaxation of rigor bends. The competitive inhibitions provide further evidence that the dynein-tubulin crossbridge cycle in flagella is similar to the actin-myosin crossbridge cycle.