Co-expressing Aplp1 and Lag3 in Aplp1 –/– /Lag3 –/– cortical neurons substantially increases binding that is greater than the sum of -syn-biotin PFF binding to Aplp1 and Lag3. Refer to supplementary Fig. 6b . ( p -values: +Aplp1 vs. +Aplp1 + Lag3 0.0001, +Lag3 vs. +Aplp1 + Lag3 0.0001).