Association of IRX1 and IRX3 in wild type, irx5-1, and irx1-1. Detergent solubilized extracts from wild type, irx5-1, and irx1-1 immunoprecipitated with anti-IRX1 antibody (IP1), anti-IRX3 antibody (IP3), or anti-IRX5 antibody (IP5). TP, total protein; W, final wash. (A and C) Blots probed with anti-IRX1 antibodies. (B) Blots probed with anti-IRX3 antibodies.