Identification of Scrib- and NOS1AP-associating proteins. A, B, Selected Scrib- (A) and NOS1AP- (B) associated proteins identified in a mass spectrometry screen (see Materials and Methods). C, Rat brain lysate was immunoprecipitated with antibodies as indicated. The resulting blot was probed with the antibodies indicated. D, NOS1AP precipitates β-Pix, Git1, and PAK confirming the results obtained from the mass spectrometry screen. E, Endogenous NOS1AP and Scrib associated with nNOS. Rat brain lysate was immunoprecipitated with the antibodies indicated and then probed as indicated. F, Endogenous Scrib and NOS1AP associate. Rat brain lysate was immunoprecipitated with the antibodies indicated. The resulting blot was probed with Scrib (upper panel) or NOS1AP (lower panel). Note a slower mobility band detected with our NOS1AP antibody (NOS1APc). G, Schematic representing three known NOS1AP isoforms. Gray boxes represent the PTB domain, and -V indicates the PDZ binding motif. H, Northern blot showing NOS1APc mRNA (arrow) is present in brain, heart, kidney, and lung.