Fig. 7. Kinase activity regulates ensconsin’s MT-binding dynamics in living cells. Two possible models by which kinase activity could affect the dynamics of ensconsin’s association with MTs in vivo. (A) The enzyme phosphorylation model involves a hypothetical enzyme that, when phosphorylated, promotes both ensconsin’s association with and dissociation from the MT. Note that this model predicts that ATP depletion or inhibition of protein kinases would bring about a decrease in ensconsin’s MT-binding dynamics, without a concomitant increase in MT-binding affinity. (B) The ensconsin phosphorylation model predicts that phosphorylation of ensconsin that occurs while it is bound to the MT enhances its dissociation, while dephosphorylation in the cytoplasm enhances its rebinding to the MT. This model would predict that ATP depletion or inhibition of protein kinases would decrease ensconsin’s MT-binding dynamics; an increase in MT-binding affinity of ensconsin would be expected to ensue unless the phosphatase shown was also dependent upon phosphorylation for its activity.