The Journal of Cell Biology, Vol 97, 832-837, Copyright © 1983 by The Rockefeller University Press
Light- and cytidine-dependent phosphatidylinositol synthesis in photoreceptor cells of the rat
SY Schmidt
Incorporation of [3H]inositol into phosphatidylinositol (Pl) in isolated
rat retinas is enhanced by light and by the addition of cytidine to the
incubation media. In retinas preincubated with [3H]inositol in dark,
[3H]inositol was chased into Pl in light by addition of unlabeled cytidine
and was chased out of Pl in light by addition of unlabeled cytidine plus
inositol. Autoradiograms of retinas show a heavy density of silver grains
over photoreceptor cell inner segments (with chase-in) and a loss of
labeling (with chase-out). Exogenous cytidine and inositol were shown to
enhance not only the turnover of Pl within photoreceptor cells but the
synthesis of Pl as well; in media supplemented with these precursors,
approximately 50% of [14C]glycerol and 25% of [32Pi]incorporated into lipid
in light were associated with Pl. These results suggest that availability
of both cytidine and inositol may play a role in the light-dependent
changes in Pl metabolism within photoreceptor cells.