preliminary molecular weight measurements indicate that the ca2+ -atpase exists as an oligomer in the native membrane : fully active enzyme in tween 80 has a minimal protein molecular weight of about 400 000 , corresponding to a trimer or tetramer of the atpase polypeptide chain , and even the inactive enzyme in deoxycholate contains a substantial fraction of dimeric protein .
C0001476
ca2
C0001473
atpase