Monoclonal antibody TA99 recognizes Tyrp1, but not Tyrp2. TA99 was used to immunoprecipitate B16 lysate as well as a lysate made from B78, a B16 subclone that does not express Tyrp1. Anti-sera raised against pep1 (C-terminus of Tyrp1) and pep8 (C-terminus of Tyrp2) were used for Western blotting. Using B16 lysate, anti-pep8 did not recognize material immunoprecipitated by TA99, while anti-pep1 bound to the expected 68 kDa protein. Using B78 lysate, no material recognized by either anti-peptide sera is immunoprecipitated by TA99.