β-Galactosidase colony filter-lift assays of GPIb/14-3-3ζ yeast 2-hybrid transformations. Reporter gene activity is reflected by expression of blue (dark) colonies, most notable with the combination of GPIbβ and full-length 14-3-3ζ, followed by GPIbβ and deletion mutant 14-3-3 (1-123) and GPIbα and full-length 14-3-3ζ. The X-gal substrate used in these assays is considered more sensitive to β-galactosidase activity than the ONPG used in the quantitative assays in Figs 2 and 3.