Fig 1: Killer immunoglobulin-like receptor (KIR) subfamily protein-protein interactions (PPIs) identified by CRISPR activation (CRISPRa) screening and phylogenetic homology analysis (PHA) approach for TAFA2.(A) ESP rank plot of the TAFA2 CRISPRa enrichment screen. (B) Trajectory plot of the top three ranking candidates for all consecutive rounds of selections in a x/y enrichment plot, size of the bubble represents the pValue (-log10). (C) Schematic representation of the domain architecture of KIR2 and KIR3 subfamily members of inhibitory KIRs. (D) Surface plasmon resonance (SPR) sensorgrams and binding kinetics for human TAFA2 (analyte) binding to KIR3DL1-ECD (ligand), sensograms were fitted using a 1:1 binding model; raw data are shown in color, fitted data are shown as black dotted lines. (E) Cell surface staining of NKL or NKL cells expressing KIR3DL1, KIR2DL1 with TAFA2:SA-647 tetramers (200 nM) and analysis by flow cytometry. (F) Dendrogram of the KIR2 and KIR3 subfamily calculated from multiple sequence alignments of KIR ECDs (gray) and PPIs (TAFA2; blue) observed in the CRISPRa screen (red) and predicted by PHA (blue). (G) Cell surface staining of K562 control cells or K562 cells lentivirally transduced with full-length KIR3DL1, KIR3DL2, KIR3DL3, KIR2DL2, or KIR2DL5A (FLAG-tagged; Figure 5—figure supplement 1C) with TAFA2:SA-647 tetramers (200 nM) and analysis by flow cytometry: full titration (1:1 dilutions; 200 nM tetramer), representative FACS histograms and quantification (200 nM tetramer). Data are represented as mean ± SD (n=3). (H) Hierarchical two-way clustering heatmap of immune cell mRNA expression data for TAFA2, KIR2, and KIR3 subfamily members.