islet-activating protein ( iap ) , pertussis toxin , is an oligomeric protein ( tamura , m. , nogimori , k. , murai , s. , yajima , m. , ito , k. , katada , t. , ui , m. , and ishii , s. ( 1982 ) biochemistry 21 , 5516-5522 ) , the biggest subunit ( mr = 28,000 , referred to as the a-protomer ) of which catalyzes transfer of the adp-ribose moiety of nad to the membrane mr = 41,000 protein .
C0033684
protein
C0025252
membrane