INVESTIGADORES
GIUSTO Norma Maria
artículos
Título:
Active labeling of phosphatidylcholines by 1-14C docosahexaenate in isolated photoreceptor membranes
Autor/es:
GIUSTO, N.M.; ILINCHETA DE BOSCHERO, M.G.; SPRECHER, H.; AVELDAÑO, M.I.
Revista:
BIOCHIMICA AND BIOPHYSICA ACTA
Editorial:
Elsevier Science Publishers B.V.
Referencias:
Año: 1986 vol. 860 p. 137 - 148
ISSN:
0006-3002
Resumen:
Isolated bovine rod outer segments and photoreceptor disks actively
incorporated [1-14C]docosahexaenoate (22:6) into phospholipids when
incubated in the presence of CoA, ATP, and Mg2+. About 80% of the
esterified fatty acid was in phosphatidylcholine (PC). Microsomal and
mitochondrial fractions incorporated as much 22:6 as rod outer segments,
but it was distributed among various phospholipids and neutral
glycerides. The isolated photoreceptor membrane thus contains an
acyl-CoA synthetase which activates the fatty acid and a
docosahexaenoyl-CoA-lysophosphatidylcholine acyltransferase activity.
The specific radioactivity of PC was higher in rod outer segments than
in the other subcellular fractions. About 2/3 of the label in
photoreceptor membrane PC was in its dipolyunsaturated molecular species
and 1/3 in hexaenes. Dipolyunsaturated PCs showed high turnover rates
of 22:6 in all three subcellular membranes, especially in mitochondria.
Retinal membranes in vitro seem to take up free [14C]22:6 from the
medium by simple diffusion or partition into the membrane lipid. The
ability of these membranes to activate and esterify [1-14C]22:6
indicates that docosahexaenoate-containing molecular species of retina
lipids, including those of photoreceptor membranes, are subject to
acylation-deacylation reactions in situ.