D domain (DD) containing polypeptides (DDpp) that specifically bind targets of interest (e.g., BCMA, CD123, CS1, HER2, AFP, and AFP p26) are provided, as are nucleic acids encoding the DDpp, vectors containing the nucleic acids and host cells containing the nucleic acids and vectors. DDpp such as DDpp fusion proteins, are also provided as are methods of making and using the DDpp. Such uses include, but are not limited to diagnostic and therapeutic applications.
