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. Author manuscript; available in PMC: 2015 Sep 27.
Published in final edited form as: Science. 2015 Feb 12;347(6229):1441–1446. doi: 10.1126/science.aaa4080

Fig. 2. Capping the dynactin filament.

Fig. 2

(A) The barbed end is capped by CapZαβ. (B) CapZαβ contains five positive residues (blue) which interact with four negative residues (orange) on Arp1. The equivalent loop in actin contains only one negative residue. (C) The short Arp11 subdomain-2 loop prevents further subunit addition to the bottom protofilament. (D) Arp11 caps the top protofilament by binding the subdomain-2 loop of Arp1-I and sterically blocking (asterisk) subsequent subunit binding. (E) The pointed end complex: p62 extends over Arp11 to touch β-actin-H. (F) p25 and p27 pack end-on to Arp11 as a continuation of the bottom protofilament.