Fig. 1.

Schematic illustration of the labeling strategy. The genomic copy of the gene encoding the target protein (Target) is fused at the 3' end to a sequence encoding the SpyTag (ST), replacing the chromosomal copy of the target’s gene. Expression is from the target’s endogenous promoter. DNA encoding a fusion of SpyoIPD (Spy) and FP (FP) is integrated at the GAL2 locus. Expression is from the GAL1 promoter (pGAL1). Shown to the right are the expressed proteins and the labeling product, with ST illustrated as the small circle fused to Target.