Talin mediates integrin signaling by binding to integrin cytoplasmic tails through its FERM domain which consists of F1, F2 and F3 subdomains. TA205, an anti-talin monoclonal antibody, disrupts actin stress fibers and focal adhesion when microinjected into fibroblasts. Here, we showed that TA205 caused an allosteric inhibition of integrin alphaIIb beta3 binding to the talin FERM domain and mapped the TA205 epitope to residues 131-150 in talin F1. Furthermore, binding of a talin rod fragment to talin head was partially inhibited by TA205. These findings suggest that talin F1 may be important in regulation of integrin binding and talin head-rod interaction.