Is the competition between microtubules and rhodopsin sufficient to explain arrestin translocation?
A version of the diffusion-mediated model of arrestin translocation has been presented in a recent study by Nair et al. (2005). They proposed that the entire phenomenon can be explained by a competition for arrestin binding between the constitutive low-affinity microtubular sites in the inner segments and the light-inducible high-affinity rhodopsin sites in the outer segments. In the dark, the affinity of microtubules is sufficient for retaining most arrestin in the inner segment compartment, whereas the formation of bleached phosphorylated rhodopsin during illumination rapidly shifts the arrestin distribution equilibrium toward the outer segments. Evidence in support of this hypothesis includes the following: the abolishment of arrestin translocation by hydroxylamine causing rapid R* decay, the slowed rate of translocation without rhodopsin phosphorylation, the correlation of arrestin return to the inner segment with rhodopsin dephosphorylation and R* decay, and impaired translocation
A version of the diffusion-mediated model of arrestin translocation has been presented in a recent study by Nair et al. (2005). They proposed that the entire phenomenon can be explained by a competition for arrestin binding between the constitutive low-affinity microtubular sites in the inner segments and the light-inducible high-affinity rhodopsin sites in the outer segments. In the dark, the affinity of microtubules is sufficient for retaining most arrestin in the inner segment compartment, whereas the formation of bleached phosphorylated rhodopsin during illumination rapidly shifts the arrestin distribution equilibrium toward the outer segments. Evidence in support of this hypothesis includes the following: the abolishment of arrestin translocation by hydroxylamine causing rapid R* decay, the slowed rate of translocation without rhodopsin phosphorylation, the correlation of arrestin return to the inner segment with rhodopsin dephosphorylation and R* decay, and impaired translocation
