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KU Loeffler, BG Kennedy, NJ Mangini; Immunolocalization of Different Plasma Membrane Ca2+ -ATPase Isoforms in Human Retina . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2610.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Plasma membrane Ca2+-ATPases (PMCAs) play a major role in Ca2+ regulation, including modulating the changes in calcium concentration in the subretinal space that accompany light/dark transitions. Four genes (ATP2B1 - ATP2B4) encode PMCA proteins termed PMCA1 - PMCA4. In previous studies, we have investigated the retinal pigment epithelium and have demonstrated the presence and location of all four PMCA proteins in this tissue. The present study examined the distribution of PMCA proteins throughout the entire retina using a monoclonal antibody (Ab) 5F10 that recognizes all PMCA isoforms as well as Abs against epitopes specific for isoforms 1, 2, and 3. Methods: Paraffin sections of a normal human eye, removed for trauma to the optic nerve, were labeled with 5F10 and with isoform-specific Abs against PMCA1, PMCA2, and PMCA3, respectively. Immunoreactivity (IR) was visualized with AEC. Results: With 5F10, IR was observed within the inner retina (mostly ganglion cells) and in photoreceptor (PhR) inner segments (mostly cones); a distinct labeling of some PhR nuclei was also seen. Anti-PMCA 1 revealed a similar staining pattern but did not show nuclear labeling. By contrast, Anti-PMCA2 also labeled PhR nuclei but no inner segments. Anti-PMCA 3, in addition to labeling of ganglion cells, PhR inner segments (again mostly cones), and the plexiform layers, could be localized to PhR synaptic terminals (cone pedicles). Finally, optic nerve neurons were stained by all Abs while glia reacted with 5F10 and anti-PMCA2 only. Corpora amylacea showed a strong reaction with anti-PMCA1. Conclusion: There are distinct differences in distribution among PMCA isoforms. Most notable, PMCA3 appears the predominant isoform at the cone synaptic terminal.
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