Fig 1: Characterization of lead de novo designed BCMA binders.(a) Yeast surface display plasmid encoding a de novo minibinder flanked by an N-terminal HA-tag and a C-terminal Myc-tag under a GAL1 promoter. (b) E.coli protein expression plasmid encoding de novo minibinder flanked by a 6xHis-tag for purification under a araBad promoter. (c) Representative gating strategy used during yeast display campaigns to identify binder hits. (d) Decoy binding of designed binder campaigns against CD19 antigen (100 nM), demonstrating variable levels of off-target reactivity. (e) Enrichment of individual binders (L10 and L11) from the RFdiffusion 5 campaign across increasing rounds of MACS. (f) Biolayer interferometry (BLI) curves and dissociation constants (Kd) values for L10 and L11 binding to BCMA antigen (100nM) from the RFdiffusion 5 campaign. (g) Enrichment of individual binders from BindCraft1 (BC1) across successive rounds of magnetic cell sorting (MACS) at decreasing concentrations, demonstrating progressive selection of high-affinity binders. (h) BLI curves and estimated Kds for additional sequencing hits from the BC1 campaign.