The present invention is directed to antibodies, and antigen-binding portions thereof, engineered to introduce amino acids for site-specific conjugation. The invention relates to engineered antibody constant region (Fc, Cγ, Cκ, and Cλ) polypeptides, and portions thereof, and antibodies comprising the polypeptides. Further, the invention relates to Fc fusion proteins comprising an engineered Fc region. The invention also relates to methods and uses of the engineered antibodies and portions for, among other things, production of antibody-drug conjugate therapeutics.
