Fig. 3. Model of the action of Halo-like proteins in bidirectional transport on MTs. (A) In the absence of Halo proteins, plus-end and minus-end motors alternate their binding to coordination machinery (possibly containing dynactin) and move RNA cargo towards either plus-ends or minus-ends of MTs. (B) Halo proteins change the steric properties of the coordination machinery, which weakens its binding to the minus-end motor and increases its binding to the plus-end motor, and results in the movement of the cargo towards the MT plus-end [adapted from Gross (Gross, 2003) and Gross et al. (Gross et al., 2003)].