The disclosure provides methods for targeting interleukin-3 receptor-expressing cells, particularly inhibiting the growth of such cells by using an interleukin-3 (IL-3) variant conjugated to a toxin that will affect cells expressing the interleukin-3 receptor. Further disclosed are interleukin-3 (IL-3) variants comprising one or more non-naturally encoded amino acids, and the structures of non-naturally encoded amino acids.
