Creatine Kinase in Human Retinal Pigment Epithelium

Retinal pigment epithelial ion transport activity, and consequent ATP consumption vary significantly as a function of photoreceptor activity. In a variety of cell types, ATP levels are maintained during high-energy usage by phosphocreatine hydrolysis, catalysed by the enzyme creatine kinase. The pre...

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Bibliographic Details
Published in:Experimental eye research 2000-02, Vol.70 (2), p.183-190
Main Authors: KENNEDY, BRIAN G., HALEY, BRIAN E., MANGINI, NANCY J.
Format: Article
Language:English
Subjects:
B-CK
Biological and medical sciences
Blotting, Western
Cells, Cultured
creatine kinase
Creatine Kinase - metabolism
cultured human retinal pigment epithelium
Electrophoresis, Agar Gel
Eye and associated structures. Visual pathways and centers. Vision
Fundamental and applied biological sciences. Psychology
Humans
Immunohistochemistry
immunolocalization
M-CK
metabolic compartmentation
Pigment Epithelium of Eye - enzymology
Vertebrates: nervous system and sense organs
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Summary:Retinal pigment epithelial ion transport activity, and consequent ATP consumption vary significantly as a function of photoreceptor activity. In a variety of cell types, ATP levels are maintained during high-energy usage by phosphocreatine hydrolysis, catalysed by the enzyme creatine kinase. The present work was designed to assess the importance of creatine kinase in retinal pigment epithelial cell metabolism. To this end, activity measurements, non-denaturing gel electrophoresis, Western blot analysis and immunohistochemistry were used to characterize creatine kinase in retinal pigment epithelium. Total creatine kinase activity in the retinal pigment epithelium is approximately 0.05 μmol ATP mg protein-1 min-1. The bulk of this activity was mediated by the B-CK isoform. However, by immunoblotting, non-denaturing gel electrophoresis and immunohistochemistry, the presence of the M-CK isoform of creatine kinase was also detected. The M-CK isoform was plasma membrane associated and predominately localized to the apical surface. Creatine kinase in the retinal pigment epithelium could function in a spatial energy shuttle that helps to sustain apical plasma membrane ion transport activity.
ISSN:0014-4835
1096-0007
DOI:10.1006/exer.1999.0766