The invention provides compositions and methods for delivering a bioactive moiety comprising at least one non-natural component into a cell cytosol of a eukaryotic cell. The bioactive moiety is linked to an A component of a bacterial toxin, a functional wild-type or modified fragment thereof, or an A component surrogate or mimetic. For delivery, the cell is contacted with the linked bioactive moiety and a corresponding B component of the bacterial toxin or a functional fragment thereof.
