Are class III and class IX myosins motorized signalling molecules?

Myosins exist that are fused to domains that harbour signalling activities. Class III myosins (NINAC) are protein kinases that play important roles in phototransduction. Class IX myosins inactivate the small G-protein Rho tha t acts as molecular switch. Because these myosins interact via their myosin head domain with actin filaments, they link signal transduction to the act in cytoskeleton. The exact motor properties of these myosins, however, rema in to be determined. (C) 2000 Elsevier Science B.V. All rights reserved.