ATP stimulated the accumulation of 45Ca2+ by chromaffin granule ghosts which contained 5 mM oxalate to trap transported calcium within the lumen. Inasmuch as the ATP-dependent 45Ca2+ transport was resistant to 25 mM ammonium acetate as well as the proton ionophore, carbonylcyanide-m-chlorophenylhydrazone, the chromaffin granule proton translocating ATPase does not provide the energy for this process. Instead, we suggest that chromaffin granules contain a calcium translocating ATPase which catalyzes the 45Ca2+ uptake directly. The observation that chromaffin granules bind to a monoclonal antibody raised against a calcium pump from bovine brain supports this hypothesis.
|Number of pages||8|
|Journal||Biochemical and Biophysical Research Communications|
|State||Published - Sep 15 1988|