BG-biotin has been successfully used in live yeast S. cerevisiae, but long incubation was necessary and the percentage of labeling was lower than anticipated. (Keppler A. et al., Nature Biotechnology 21, 2003). With genetic modifications disabling some of the MDR transpoter proteins from yeast routine labeling of intracellular SNAP-tag in yeast is possible (McMurray, M.A. and Thorner, J. (2008) Current Biology, 18, 1203).