we reported previously that the purified mutant protein could be converted to the factor ixa beta form by factor xia/ca2+ at a rate similar to that in the case of normal factor ix , but the resulting mutant factor ixa beta could not activate factor x in the presence of factor viii , ca2+ , and phospholipids ( yoshioka , a. et al . ( 1986 ) thromb . res . 42 , 595-604 ) .
C0015494
factor ixa
C0015491
factor ix