To provide a method for alleviating rejection in xenograft therapy, a method for maintenance of a xenotransplanted tissue and to provide a rejection resistant transgenic organ.

This invention provides a DNA sequence encoding a porcine Gal α (1, 3) galactosyl transferase and a clone containing the sequence. The porcine Gal α (1, 3) galactosyl transferase produces the Gal alpha (1, 3) Gal epitope on the surfaces of porcine cells. This epitope is recognized by human anti-Gal α (1, 3) Gal antibodies which are responsible for hyperacute rejection of xenotransplanted pig cells, tissues and organs. The invention further provides an antagonist which changes the action of the antibodies, as a method for reducing such hyperacute rejection.