Biosynthesis of glycerolipid molecular species in photoreceptor membranes of frog retina
- Baylor College of Medicine, Houston, TX (USA)
Phospholipid (PL) molecular species of vertebrate retinal photoreceptor cells are unique in that they contain two polyunsaturated fatty acids per molecule. Docosahexaenoic acid (22:6 {omega}3) is the major component of these dipolyunsaturate species (DPS), which also contain 20:4{omega}6, 22:4{omega}6, 22:5{omega}6, and 22:5{omega}3. We have studied the de novo synthesis and metabolism of the (DPS) and other PL molecular species in frog rod outer segments (ROS) following intravitreal injection of 2-({sup 3}H)-glycerol. At 1, 2, 4, and 8 days after injection, ROS were prepared, PL extracted, and phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylserine (PS) isolated. PC, PE, and PS were converted to diglycerides (DG's) with phospholipase C. DG's were derivatized, fractionated into molecular species by HPLC, quantitated, and counted for radioactivity. The following were observed: (1) Specific activities (SA) of the PC DPS were 3-5 times higher than the same species in either PE or PS. (2) SA of the PC monopolyunsaturate species (MPS) (species which contain 22:6{omega}3 and/or 16:0 or 18:0) were 3-5 times lower than the SA of the PC DPS. In contrast, SA of PE MPS were 2-5 times higher than the SA of the PE DPS. (3) The major PS MPS synthesized contained 18:0 and 22:6{omega}3. SA of that species were similar to SA of the PS DPS. The data support the suggestion that PC DPS are synthesized and/or incorporated in ROS at a greater rate than the same species in either PE or PS. Our study thus provides evidence for different rates of synthesis and/or incorporation of the various molecular species of PC, PE, and PS in ROS.
- OSTI ID:
- 7018744
- Report Number(s):
- CONF-870644-; TRN: 90-007821
- Journal Information:
- FASEB (Federation of American Societies for Experimental Biology) Journal; (USA), Vol. 46:6; Conference: 78. annual meeting of the American Society of Biological Chemists conference, Philadelphia, PA (USA), 7-11 Jun 1987
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GLYCOLIPIDS
BIOSYNTHESIS
RETINA
METABOLISM
BIOCHEMICAL REACTION KINETICS
CARBOXYLIC ACIDS
FROGS
GLYCEROL
INJECTION
LIPASES
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ALCOHOLS
AMPHIBIANS
ANIMALS
AQUATIC ORGANISMS
BODY
BODY AREAS
CARBOHYDRATES
CARBOXYLESTERASES
ENZYMES
ESTERASES
EYES
FACE
HEAD
HYDROGEN COMPOUNDS
HYDROLASES
HYDROXY COMPOUNDS
INTAKE
ISOTOPE APPLICATIONS
KINETICS
LIPIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
REACTION KINETICS
SACCHARIDES
SENSE ORGANS
SYNTHESIS
VERTEBRATES
550501* - Metabolism- Tracer Techniques