ACF7 is required to tether microtubules to the actin cortex.

In order to serve as effective tracks for cargo transportation in cells, microtubules must be able to transiently attach to the cell periphery. In order to orient transport and movement, microtubules transiently tether to cortical actin patches, which can be dynamically deposited beneath the plasma membrane in response to polarizing cues, such as cell-cell contacts.

ACF7 is a large, cytoskeletal crosslinking protein with actin and microtubule binding domains. When ACF7 is missing, actin-microtubule connections are weakened. In this movie, you can see what happens as a consequence. At the periphery of ACF7 null (KO) endodermal cells, microtubules continue growing and fail to tether/pause at the actin cortex. In wild-type (WT) cells, microtubules normally stop growing and tether/pause at the cell margin, before undergoing "dynamic instability". The cells for this movie were visualized live, by using GFP-GAS2, a fluorescent fusion protein containing the microtubule binding domain of ACF7 (see Kodama et al. Cell 115, 343-354, 2003).

 ACF7 is required to tether microtubules to the actin cortex.In order to serve as effective tracks for cargo transportation in cells, microtubules must be able to transiently attach to the