Talin binds directly to Tiam1. (A) Schematic diagram of the domain organization of talin1 and its fragments. (B) Lysates of COS7 cells expressing Tiam1-HA and the indicated myc-talin1 fragments were immunoprecipitated with anti-myc antibody. Tiam1 was detected only in the eluates of talin1 1–433 aa and 102–656 aa. Top and bottom panels show immunoblots with anti-HA and anti-myc antibody, respectively. Asterisk indicates immunoglobulin heavy chain. (C) Delineation of the Tiam1-binding region within the talin1 head domain. The fragments used and results are indicated on the top. Tiam1 was most abundant in the eluates of beads coated with talin1 fragments that possessed the F3 subdomain. (D) Sensorgrams of the association and dissociation phases for binding of GST-Tiam1-PDZ4 and His-talin1 1–433 aa. Talin1 (1–433 aa; 0.42–3.3 µM) was injected onto a surface coated with GST-Tiam1-PDZ4. Results are representative of more than three experiments.