Light-mediated breakdown of phosphatidylinositol-4,5-bisphosphate in isolated rod outer segments of frog photoreceptor

Biochem Biophys Res Commun. 1985 Apr 30;128(2):954-9. doi: 10.1016/0006-291x(85)90139-1.

Abstract

When isolated frog (Rana catesbeiana) rod outer segment (ROS) fragments were incubated with [gamma-32P]ATP in the dark, only two of phospholipids, i.e., phosphatidylinositol-4-phosphate (DPI) and phosphatidic acid (PA) incorporated 32P. Upon addition of DPI (100 microM), considerable amount of 32P was incorporated into phosphatidylinositol-4,5-bisphosphate (TPI) as well as DPI and PA. Exposure of the ROS membranes to 5 sec flash of light resulted in approx. 20% decrease in the labeled TPI, while no significant effect was observed on DPI and PA. It was also observed that Ca2+ markedly accelerated the production of PA in the dark, while it reduced the 32P-incorporation into TPI. These results suggest that there is light- and/or Ca2+-dependent TPI-specific phospholipase C in ROS of vertebrate photoreceptors.

MeSH terms

  • Animals
  • Calcium / metabolism
  • Chromatography, Thin Layer
  • Light*
  • Phosphatidylinositol 4,5-Diphosphate
  • Phosphatidylinositols / metabolism
  • Photoreceptor Cells / metabolism*
  • Rana catesbeiana
  • Rod Cell Outer Segment / metabolism*

Substances

  • Phosphatidylinositol 4,5-Diphosphate
  • Phosphatidylinositols
  • Calcium