(A) SGA screen summary showing examples of hits (quadruplicate spots are highlighted) on 5-FOA plates (left panel), screen outcomes from two independent sec31-GS13 screens and overlap with sec13Δ screen hits (middle panel), and a list of overlap hits (right panel) that were further confirmed by direct crosses with sec13Δ or sec13Δ erp1Δ (*) strains. ERP2 is functionally related to other hits (highlighted in red) but was identified only in sec31-GS13 screens. (B) Most confirmed BST genes act in GPI-AP remodeling and trafficking pathways. EMP24 and GUP1, though not identified in the screens, conferred bst phenotypes upon direct testing. (C) Growth phenotypes of bstΔ sec13Δ strains generated by direct crosses on 5-FOA at 25°C. (*) The phenotypes of gup1Δ sec13Δ and per1Δ sec13Δ depend on the strain background. (D) Maturation (trafficking) of the GPI-AP Gas1p in p24 and erv29Δ mutants, as revealed by pulse-chase experiments. Maturation of a soluble protein, CPY, is shown for comparison; ‘p’ marks precursor (ER) forms, “m” indicates mature (post-Golgi) forms.