The inhibition of the calcium transport ATPase of the sarcomplasmic reticulum by fluorescamine: evidence for an oligomeric functional unit of the calcium transport system.

The labeling of the protein moiety of the sarcoplasmic calcium transport ATPase by fluorescamine suppresses calcium transport, calcium dependent ATPase activity, protein phosphorylation by [gamma-32P]ATP and [32P]phosphate at different extent of amino group substitution. For the hydrolysis of para nitrophenylphosphate by the calcium transport ATPase, it is shown that the relationship between the extent of amino group labelling can considerably be altered by the temperature and the presence of ethyleneglycol. It is shown that the amino residues of the phosphatidylethanolamine moiety do not contribute to the inhibiting effect of fluorescamine labelling. The observations suggest that the different functions of the calcium transport system are based on the cooperation of a varying number of calcium transport ATPase molecules.