Add a new actin nucleator to the mix. Rashmi Ahuja, Michael Kessels, Britta Qualmann (Leibniz Institute for Neurobiology, Magdeburg, Germany), and colleagues identify Cordon-Bleu (Cobl) as a nucleator of actin filaments.
“Previously, there were really only two known vertebrate actin nucleators: formins and the Arp2/3 complex,” says Qualmann. “That's surprising if you consider the wealth of different actin structures that form.”
While studying proteins that interface with Arp2/3 and link actin polymerization to vesicle trafficking, the team noticed that new actin filaments still formed in extracts lacking Arp2/3. They decided it was time to fish for a new nucleator.
Using yeast two-hybrid analyses with those actin/vesicle linking proteins as bait, the group pulled out Cobl. Unlike Arp2/3 and its output of branched actin networks, Cobl created unbranched filaments similar to those made by formins. But formins are weak compared with Cobl, which polymerized filaments at...
