Isoform PMCA3 of the plasma membrane calcium pump (ATPase) is localized in the inner plexiform layer of rat retina

Abstract

Regulation of cytosolic Ca2+ is of critical importance for maintaining normal cellular function in the nervous system. Control of calcium homeostasis involves the Ca2+-ATPase of plasma membrane (PMCA) and other transporters. The presence of these regulatory molecules may not be a fixed characteristic of cells in a general sense. Rather, each class of cells may utilize a unique combination of transporters to maintain homeostatic control. In addition, unique distributions of transport molecules and their isoforms may exist in individual parts of cells imparting unique transport signatures to specific cell types. PMCA is a major regulator of calcium transport under normal physiological conditions. In order to understand localization of PMCA isoforms in specific cells we have localized specific PMCA mRNAs by in situ hybridization and translated PMCA protein by immunocytochemistry. The present work is focused on localization of PMCA3, an isoform predominantly known to exist in brain and skeletal muscle, but not previously investigated in retina. We previously showed that mRNA encoding rat plasma membrane Ca2+-ATPase isoform PMCA3 was localized in the granule cell layer of the cerebellum.