Different sensitivity to trypsin of the human platelet plasma and intracellular membrane Ca2+ pumps.

摘要: The Ca2+ pumps associated with human platelet plasma and intracellular membranes have been further characterized by their sensitivity to trypsin. (a) Tryptic degradation of the Ca2+-ATPases has followed immunoblotting. It resulted in fragmentation into peptides 80, 55, 35, 24 kDa for both enzymes. Subcomplete hydrolysis obtained a ratio trypsin/membrane protein 0.05-0.1 two total disappearance 100-, 80-, 35-kDa fragments. However, maximum was reached within 1 min enzyme but needed 5 incubation membrane enzyme. (b) This effect trypsin correlated its on Ca2+-ATPase activities. showed inhibition 50-60% which using trypsin/protein 0.1 incubation. A much higher observed because 80% after only (c) Finally, transport systems studied different reactivities; uptake vesicles inhibited 20-25%, this In contrast, difficult detect treatment. Taken together, results show that can be distinguished sensitivity.