Figure 4

APP and Itgβ1 biochemically interact. (a) CHO cells were transiently transfected with constructs as shown. Co-immunoprecipitations of the resultant lysates were then performed with anti-FLAG agarose. Western blots for the amino terminus of APP (anti-APP; 22C11; Chemicon) or Itgβ1 (Cell Signaling): upper panels are western blots of lysates and lower panels show western blots of FLAG-immunoprecipitations (IP). The band denoted by the single asterisk is believed to be a background band. The band denoted by the double asterisks is the heavy chain of IgG. (b) CHO cells were transiently transfected with APP and Itgβ1-FLAG or another carboxy-terminally tagged type I-transmembrane domain protein, angiotensin converting enzyme (ACE). Co-immunoprecipitations of the resultant lysates were then performed with anti-FLAG agarose and western blotted (WB) for APP or FLAG, as shown. (c) CHO cells were transiently transfected with Itgβ1-FLAG and APP, APLP1, or APLP2. Co-immunoprecipitations of the resultant lysates were then performed with anti-FLAG agarose and western blotted for APLP1, APLP2, or Itgβ1, as shown. (d) Lysates from CHO cells, E18 rat primary neurons, rat cortex, or transfected CHO cells were immunoprecipitated for Itgβ1 and western blotted for APP. (e) Lysates from total mouse brain were immunoprecipitated with antibodies directed to APP or Tbr1 (used as a control) for 30 minutes or overnight (O/N) and western blotted for Itgβ1, APP, or transferrin receptor as a negative control.