Schematics of array-based methods for interaction analysis. (A) Protein array. Purified proteins are arrayed and challenged with a labeled peptide. (B) NAPPA. The cDNA of the proteins to be screened is genetically fused to a tag, immobilized on a microarray surface and in vitro transcribed and translated. The tag is used to capture the expressed protein on the surface of the microarray (1). The immobilized proteins are screened for interactions with the target protein or peptide, that can then be detected by a suitable antibody (2). (C) Peptide array. Peptides are synthesized on a surface, screened for interaction with a target protein. Bound protein can be detected by a suitable antibody. (D) PRISMA. Peptides are synthesized on a cellulose membrane and incubated with a cell extract (1). Unbound proteins are washed away (2). The membrane is incubated with a cell extract for affinity enrichment of binders, the peptide spots are isolated and the identities of the enriched proteins are then determined through MS (3).