Biomaterial Database

Lipid composition of lens plasma membrane fractions enriched in fiber junctions. 1991

C R Fleschner, and R J Cenedella

Department of Biochemistry, Kirksville College of Osteopathic Medicine, MO 63501.

Little is known about the lipid environment of lens fiber junctions, the plasma membrane structure proposed to be responsible for passage of low molecular weight metabolites between adjacent lens fiber cells. Plasma membranes of the ocular lens are especially rich in fiber junctions. The resistance of junctional domains to disruption by detergent or alkali treatment provides the opportunity to isolate a lens plasma membrane fraction enriched in fiber junctions. When examined by electron microscopy, the fiber junction fraction prepared from bovine lenses was enriched with junctional structures by about twofold when compared to total plasma membrane. We compared the protein, phospholipid, and cholesterol concentration of total plasma membrane with fiber junctional membrane from rat and cow lens and from aged normal cataractous human lenses. The principal finding was that junctional membrane contained 20-40% more total lipid than that of the total plasma membrane. This was due to a proportionate increase in the relative content (mg/mg protein) of both phospholipid and cholesterol. Exclusive of one exception (nucleus of bovine lens), the cholesterol/phospholipid molar ratios of the two fractions were similar. In the bovine nucleus, the cholesterol/phospholipid molar ratio was substantially higher in the fiber junctional-enriched membrane fraction than in the total plasma membrane, suggesting a special association of cholesterol with bovine nuclear fiber junctions. The relative lipid compositions of the plasma membrane and fiber junction-enriched fractions from human normal and cataractous lenses were similar, suggesting that human senile cataractogenesis involves changes in the lens plasma membrane more subtle than would be reflected by gross changes in the membrane lipid composition.

UI	MeSH Term	Description	Entries
D007365	Intercellular Junctions	Direct contact of a cell with a neighboring cell. Most such junctions are too small to be resolved by light microscopy, but they can be visualized by conventional or freeze-fracture electron microscopy, both of which show that the interacting CELL MEMBRANE and often the underlying CYTOPLASM and the intervening EXTRACELLULAR SPACE are highly specialized in these regions. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p792)	Cell Junctions,Cell Junction,Intercellular Junction,Junction, Cell,Junction, Intercellular,Junctions, Cell,Junctions, Intercellular
D007908	Lens, Crystalline	A transparent, biconvex structure of the EYE, enclosed in a capsule and situated behind the IRIS and in front of the vitreous humor (VITREOUS BODY). It is slightly overlapped at its margin by the ciliary processes. Adaptation by the CILIARY BODY is crucial for OCULAR ACCOMMODATION.	Eye Lens,Lens, Eye,Crystalline Lens
D008297	Male		Males
D010743	Phospholipids	Lipids containing one or more phosphate groups, particularly those derived from either glycerol (phosphoglycerides see GLYCEROPHOSPHOLIPIDS) or sphingosine (SPHINGOLIPIDS). They are polar lipids that are of great importance for the structure and function of cell membranes and are the most abundant of membrane lipids, although not stored in large amounts in the system.	Phosphatides,Phospholipid
D011919	Rats, Inbred Strains	Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding.	August Rats,Inbred Rat Strains,Inbred Strain of Rat,Inbred Strain of Rats,Inbred Strains of Rats,Rat, Inbred Strain,August Rat,Inbred Rat Strain,Inbred Strain Rat,Inbred Strain Rats,Inbred Strains Rat,Inbred Strains Rats,Rat Inbred Strain,Rat Inbred Strains,Rat Strain, Inbred,Rat Strains, Inbred,Rat, August,Rat, Inbred Strains,Rats Inbred Strain,Rats Inbred Strains,Rats, August,Rats, Inbred Strain,Strain Rat, Inbred,Strain Rats, Inbred,Strain, Inbred Rat,Strains, Inbred Rat
D002386	Cataract	Partial or complete opacity on or in the lens or capsule of one or both eyes, impairing vision or causing blindness. The many kinds of cataract are classified by their morphology (size, shape, location) or etiology (cause and time of occurrence). (Dorland, 27th ed)	Cataract, Membranous,Lens Opacities,Pseudoaphakia,Cataracts,Cataracts, Membranous,Lens Opacity,Membranous Cataract,Membranous Cataracts,Opacities, Lens,Opacity, Lens,Pseudoaphakias
D002417	Cattle	Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.	Beef Cow,Bos grunniens,Bos indicus,Bos indicus Cattle,Bos taurus,Cow,Cow, Domestic,Dairy Cow,Holstein Cow,Indicine Cattle,Taurine Cattle,Taurus Cattle,Yak,Zebu,Beef Cows,Bos indicus Cattles,Cattle, Bos indicus,Cattle, Indicine,Cattle, Taurine,Cattle, Taurus,Cattles, Bos indicus,Cattles, Indicine,Cattles, Taurine,Cattles, Taurus,Cow, Beef,Cow, Dairy,Cow, Holstein,Cows,Dairy Cows,Domestic Cow,Domestic Cows,Indicine Cattles,Taurine Cattles,Taurus Cattles,Yaks,Zebus
D002462	Cell Membrane	The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.	Plasma Membrane,Cytoplasmic Membrane,Cell Membranes,Cytoplasmic Membranes,Membrane, Cell,Membrane, Cytoplasmic,Membrane, Plasma,Membranes, Cell,Membranes, Cytoplasmic,Membranes, Plasma,Plasma Membranes
D002645	Chickens	Common name for the species Gallus gallus, the domestic fowl, in the family Phasianidae, order GALLIFORMES. It is descended from the red jungle fowl of SOUTHEAST ASIA.	Gallus gallus,Gallus domesticus,Gallus gallus domesticus,Chicken
D002784	Cholesterol	The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils.	Epicholesterol