INVESTIGADORES
GIUSTO Norma Maria
artículos
Título:
Synthesis of polyphosphoinositides in vertebrate photoreceptor membranes
Autor/es:
GIUSTO, N.M.; ILINCHETA DE BOSCHERO, M.G.
Revista:
BIOCHIMICA AND BIOPHYSICA ACTA
Editorial:
Elsevier Science Pu
Referencias:
Año: 1986 vol. 877 p. 440 - 446
ISSN:
0006-3002
Resumen:
Rod outer segments isolated from bovine retinas incorporated 32P into phospholipids after incubation with [γ-32p]atp in a Mg2+-containing
medium. Only phosphatidylinositol 4-phosphate, phosphatidylinositol
4,5-bisphosphate and phosphatidate were labelled. The incorporation of
label into lipids was detected as early as 20 s after the start of
incubation and the products were stable for at least 10 min. The
reactions were time, protein and ATP-concentration dependent. Entire rod
outer segments showed higher diacylglycerol kinase and lower
phosphatidylinositol and phosphatidylinositol 4-phosphate kinase
activities than the disc membranes obtained from them. Exogenously added
phosphatidylinositol (up to 1 inM) in the presence of Triton X-100
increased phosphatidylinositol 4-phosphate and phosphatidylinositol
4,5-bisphosphate labelling in rod outer segments (8- and 6-fold,
respectively). Triton X-100 at a concentration of 0.4% stimulated
phosphorylation of endogenous phosphoinositides. Diacylglycerol kinase
activity was largely suppressed by the detergent, but this effect was
partially reversed by addition of phosphatidylinositol. It is suggested
that the rod outer segments contain phosphatidylinositol kinase and
phosphatidylinositol 4-phosphate kinase bound to disc membranes, as well
as an active diacylglycerol kinase occurring either as a soluble or a
peripherally bound protein in disc membranes.