Abstract: Elucidating the function of proteins in mammalian cells is particularly challenging due to the inherent complexity of these systems. Methods to study protein function in living cells ideally perturb the activity of only the protein of interest but otherwise maintain the natural state of the host cell or organism. Ligand-dependent inteins offer single-protein specificity and other desirable features as an approach to control protein function in cells post-translationally. Some aspects of this invention provide second-generation ligand-dependent inteins that splice to substantially higher yields and with faster kinetics in the presence of the cell-permeable small molecule 4-HT, especially at 37° C., while exhibiting comparable or improved low levels of back-ground splicing in the absence of 4-HT, as compared to the parental inteins. These improvements were observed in four protein contexts tested in mammalian cells at 37° C., as well as in yeast cells assayed at 30° C. or 37° C.

Abstract: Elucidating the function of proteins in mammalian cells is particularly challenging due to the inherent complexity of these systems. Methods to study protein function in living cells ideally perturb the activity of only the protein of interest but otherwise maintain the natural state of the host cell or organism. Ligand-dependent inteins offer single-protein specificity and other desirable features as an approach to control protein function in cells post-translationally. Some aspects of this invention provide second-generation ligand-dependent inteins that splice to substantially higher yields and with faster kinetics in the presence of the cell-permeable small molecule 4-HT, especially at 37° C., while exhibiting comparable or improved low levels of background splicing in the absence of 4-HT, as compared to the parental inteins. These improvements were observed in four protein contexts tested in mammalian cells at 37° C., as well as in yeast cells assayed at 30° C. or 37° C.

Abstract: Elucidating the function of proteins in mammalian cells is particularly challenging due to the inherent complexity of these systems. Methods to study protein function in living cells ideally perturb the activity of only the protein of interest but otherwise maintain the natural state of the host cell or organism. Ligand-dependent inteins offer single-protein specificity and other desirable features as an approach to control protein function in cells post-translationally. Some aspects of this invention provide second-generation ligand-dependent inteins that splice to substantially higher yields and with faster kinetics in the presence of the cell-permeable small molecule 4-HT, especially at 37° C., while exhibiting comparable or improved low levels of background splicing in the absence of 4-HT, as compared to the parental inteins. These improvements were observed in four protein contexts tested in mammalian cells at 37° C., as well as in yeast cells assayed at 30° C. or 37° C.