U. Pick, S. Karlish
Nov 20, 1980
Citations
3
Influential Citations
140
Citations
Quality indicators
Journal
Biochimica et biophysica acta
Abstract
Fluorescein isothiocyanate is a highly specific inhibitor of the Ca2+-ATPase from sarcoplasmic reticulum. The Ca2+ pumping is inhibited completely at a fluorescein isothiocyanate concentration half that of the ATPase protein, indicating that the protein is at least a dimer. ATP protected specifically against fluorescein isothiocyanate inhibition, indicating that fluorescein isothiocyanate may react at the nucleotide binding site of the ATPase (probably with a reactive lysine residue). The fluorescein is incorporated almost exclusively into the 105 kdalton catalytic polypeptide of the ATPase and digestion by trypsin gives rise to a fluorescein-labelled 45 kdalton fragment. Conformational changes induced by addition of Ca can be studied conveniently with the fluorescein-labelled ATPase.