scholarly journals The Ca2+-activated polyphosphoinositide phosphodiesterase of human and rabbit neutrophil membranes

1984 ◽  
Vol 221 (2) ◽  
pp. 477-482 ◽  
Author(s):  
S Cockcroft ◽  
J M Baldwin ◽  
D Allan
Keyword(s):  
Fatty Acid Composition ◽  
Plasma Membrane ◽  
Fatty Acid ◽  
Phospholipase C ◽  
Acid Composition ◽  
Membrane Fraction ◽  
Plasma Membranes ◽  
Degradation Products ◽  
Diacylglycerol Kinase ◽  
Plasma Membrane Fraction

Addition of Ca2+ to a plasma-membrane fraction derived from human or rabbit neutrophils led to the specific breakdown of polyphosphoinositides. The degradation products were identified as diacylglycerol and inositol bis- and tris-phosphate, thus demonstrating the presence of a Ca2+-activated phospholipase C. The newly generated diacylglycerol resembled the polyphosphoinositides in its fatty acid composition, and in the presence of MgATP2- it was converted into phosphatidate. These results therefore demonstrate the presence in neutrophil plasma membranes not only of polyphosphoinositide phosphodiesterase but also of diacylglycerol kinase.

scholarly journals Within and between breed differences in freezing tolerance and plasma membrane fatty acid composition of boar sperm

Reproduction ◽  
2006 ◽  
Vol 131 (5) ◽  
pp. 887-894 ◽  
Author(s):  
K E Waterhouse ◽  
P O Hofmo ◽  
A Tverdal ◽  
R R Miller
Keyword(s):  
Fatty Acids ◽  
Fatty Acid Composition ◽  
Plasma Membrane ◽  
Fatty Acid ◽  
Survival Rate ◽  
Acid Composition ◽  
Plasma Membranes ◽  
Female Reproductive Tract ◽  
Freezing And Thawing ◽  
Acrosome Integrity

The response of sperm to cryopreservation and the fertility of frozen–thawed semen varies between species. Besides species differences in sperm physiology, structure and biochemistry, factors such as sperm transport and female reproductive tract anatomy will affect fertility of frozen–thawed semen. Therefore, studying differences in sperm cryotolerance between breeds and individuals instead of between species may reveal sources of variability in sperm cryotolerance. In the present study, the effect of cooling, re-warming and freezing and thawing on plasma membrane and acrosome integrity of sperm within and between Norwegian Landrace and Duroc breeds was studied. Furthermore, the relation between post-thaw survival rate and fatty acid composition of the sperm plasma membranes was investigated. Flow cytometry assessments of plasma membrane and acrosome integrity revealed no significant differences between breeds; however there were significant male-to-male variations within breeds in post-thaw percentages of live sperm (plasma membrane intact). The most abundant fatty acids in the plasma membranes from both breeds were palmitic acid (16:0), stearic acid (18:0), oleic acid (18:1, n-9), docosapentaenoic acid (22:5, n-6) and docosahexaenoic acid (22:6, n-3). The ratio of ∑ 22:5, n-6 and 22:6, n-3/∑ all other membrane fatty acids was significantly related to survival rate (plasma membrane integrity) of sperm for both Norwegian Landrace (correlation coefficient (rs) = 0.64,P< 0.05) and Duroc (rs= 0.67,P< 0.05) boars. In conclusion, male-to-male differences in sperm survival rate after freezing and thawing may be partly related to the amount of long-chain polyunsaturated fatty acids in the sperm plasma membranes.

scholarly journals Plasma membrane association of Acanthamoeba myosin I.

1989 ◽  
Vol 109 (4) ◽  
pp. 1519-1528 ◽  
Author(s):  
H Miyata ◽  
B Bowers ◽  
E D Korn
Keyword(s):  
Plasma Membrane ◽  
Binding Site ◽  
Heavy Chain ◽  
Membrane Fraction ◽  
Plasma Membranes ◽  
Actin Binding ◽  
Plasma Membrane Fraction ◽  
Myosin I ◽  
Membrane Bound ◽  
Actin Binding Site

Myosin I accounted for approximately 2% of the protein of highly purified plasma membranes, which represents about a tenfold enrichment over its concentration in the total cell homogenate. This localization is consistent with immunofluorescence analysis of cells that shows myosin I at or near the plasma membrane as well as diffusely distributed in the cytoplasm with no apparent association with cytoplasmic organelles or vesicles identifiable at the level of light microscopy. Myosin II was not detected in the purified plasma membrane fraction. Although actin was present in about a tenfold molar excess relative to myosin I, several lines of evidence suggest that the principal linkage of myosin I with the plasma membrane is not through F-actin: (a) KI extracted much more actin than myosin I from the plasma membrane fraction; (b) higher ionic strength was required to solubilize the membrane-bound myosin I than to dissociate a complex of purified myosin I and F-actin; and (c) added purified myosin I bound to KI-extracted plasma membranes in a saturable manner with maximum binding four- to fivefold greater than the actin content and with much greater affinity than for pure F-actin (apparent KD of 30-50 nM vs. 10-40 microM in 0.1 M KCl plus 2 mM MgATP). Thus, neither the MgATP-sensitive actin-binding site in the NH2-terminal end of the myosin I heavy chain nor the MgATP-insensitive actin-binding site in the COOH-terminal end of the heavy chain appeared to be the principal mechanism of binding of myosin I to plasma membranes through F-actin. Furthermore, the MgATP-sensitive actin-binding site of membrane-bound myosin I was still available to bind added F-actin. However, the MgATP-insensitive actin-binding site appeared to be unable to bind added F-actin, suggesting that the membrane-binding site is near enough to this site to block sterically its interaction with actin.

scholarly journals Activation of rat liver plasma-membrane diacylglycerol kinase by vasopressin and phenylephrine

1988 ◽  
Vol 255 (3) ◽  
pp. 923-928 ◽  
Author(s):  
M H Rider ◽  
A Baquet
Keyword(s):  
Plasma Membrane ◽  
Rat Liver ◽  
Membrane Fraction ◽  
Kinase Activity ◽  
Diacylglycerol Kinase ◽  
Liver Plasma Membrane ◽  
Plasma Membrane Fraction ◽  
In Cells

Plasma-membrane fractions were prepared from the livers of rats injected with 0.15 M-NaCl (controls) or vasopressin (1 nmol/kg body wt.). When assayed in the presence of deoxycholate, vasopressin increased the Vmax. of plasma-membrane diacylglycerol kinase 2-4-fold, and the apparent Km of the enzyme for 1,2-dioleoyl-sn-glycerol was doubled. The effect of vasopressin on the Vmax. of plasma-membrane diacylglycerol kinase was twice as great between pH 7 and 8.5 than at pH 6 or 6.5. Vasopressin doubled the activity of diacylglycerol kinase in the plasma-membrane fraction when the enzyme was assayed with phosphatidylserine rather than deoxycholate as stimulator, and when either 1-stearoyl-2-arachidonoyl-sn-glycerol or 1,2-dioleoyl-sn-glycerol was the substrate. In perfused livers vasopressin (10 nM) increased the Vmax. of plasma-membrane diacylglycerol kinase 2-fold, and phenylephrine (3 microM) gave a similar effect. Vasopressin doubled diacylglycerol kinase activity in hepatocytes that had been preincubated for 55 min, but not in cells that had only been preincubated for 15 min.

scholarly journals Diet fat influences liver plasma-membrane lipid composition and glucagon-stimulated adenylate cyclase activity

1983 ◽  
Vol 212 (3) ◽  
pp. 573-583 ◽  
Author(s):  
P J Neelands ◽  
M T Clandinin
Keyword(s):  
Fatty Acid Composition ◽  
Plasma Membrane ◽  
Fatty Acid ◽  
Adenylate Cyclase ◽  
Acid Composition ◽  
Unsaturated Fatty Acid ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Fat Intake ◽  
Omega 6

Rats were fed diets that differed in fatty acid composition or in the proportion of energy derived from fat to determine if alteration of dietary fat intake influences the structural lipid composition of liver plasma membrane and the expression of an associated hormone-receptor-mediated function. Weanling rats were fed 9% (w/w) or 20% (w/w) low-erucic acid rape-seed oil or 9% (w/w) soya-bean oil for 24 days. Plasma membranes were isolated and the effect of diet fat on the fatty acid composition of phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol and sphingomyelin was determined. Diet fat significantly altered total saturated and (omega-9) and (omega-6)-unsaturated fatty acid composition in addition to the (omega-6)- to (omega-3)-unsaturated fatty acid ratio in these polar lipids. Feeding the high-fat diet increased the (omega-6)- to (omega-3)-unsaturated fatty acid ratio and the (omega-9)-unsaturated fatty acid content in all lipids except sphingomyelin. Assay of glucagon-stimulated adenylate cyclase activity at both high and low glucagon concentrations indicated that high-fat intake also decreased cyclic AMP formation. In a second experiment the fat intake was held constant (40% of energy) and oleic acid was substituted for linoleic acid by blending high- and low-linoleic acid-type safflower oils. This experiment established that a dose-response relationship exists between dietary intake of fatty acid and the fatty acid composition of plasma-membrane phospholipids. Specific diet-induced transitions in membrane phospholipid fatty acid composition were paralleled by changes in glucagon-stimulated adenylate cyclase activity. This study suggests that transitions in dietary fat intake can alter a hormone-receptor-mediated enzyme function in vivo by changing the surrounding lipid environment.

scholarly journals BIOCHEMICAL AND MORPHOLOGICAL COMPARISON OF PLASMA MEMBRANE AND MILK FAT GLOBULE MEMBRANE FROM BOVINE MAMMARY GLAND

1970 ◽  
Vol 44 (1) ◽  
pp. 80-93 ◽  
Author(s):  
T. W. Keenan ◽  
D. James Morré ◽  
Diane E. Olson ◽  
W. N. Yunghans ◽  
Stuart Patton
Keyword(s):  
Fatty Acid Composition ◽  
Plasma Membrane ◽  
Fatty Acid ◽  
Acid Composition ◽  
Milk Fat ◽  
Major Protein ◽  
Thin Sections ◽  
Milk Fat Globule ◽  
Fat Globule ◽  
Milk Fat Globule Membranes

Purified plasma membrane fractions from lactating bovine mammary glands and membranes of milk fat globules from the same source were similar in distribution and fatty acid composition of phospholipids. The sphingomyelin content of the phospholipid fraction of both membranes was higher than in these fractions from other cell components, ß-carotene, a constituent characteristic of milk fat, was present in the lipid fraction of the plasma membrane. Cholesterol esters of plasma membrane were similar in fatty acid composition to those of milk fat globule membranes. Disc electrophoresis of either membrane preparation on polyacrylamide gels revealed a single major protein component characteristic of plasma membrane from other sources. Distinct morphological differences between plasma membrane and milk fat globule membranes were observed in both thin sections and in negatively stained material. Plasma membrane was vesicular in appearance while milk fat globule membranes had a platelike aspect. These observations are consistent with derivation of fat globule membrane from plasma membrane accompanied by structural rearrangement of membrane constituents.

scholarly journals PREPARATION AND CHARACTERIZATION OF A PLASMA MEMBRANE FRACTION FROM ISOLATED FAT CELLS

1970 ◽  
Vol 44 (2) ◽  
pp. 417-432 ◽  
Author(s):  
Daniel W. McKeel ◽  
Leonard Jarett
Keyword(s):  
Plasma Membrane ◽  
Cytochrome C ◽  
Membrane Fraction ◽  
Plasma Membranes ◽  
Reductase Activity ◽  
Fat Cells ◽  
Isolated Fat Cells ◽  
Adenyl Cyclase Activity ◽  
Cytochrome C Reductase ◽  
Plasma Membrane Fraction

A rapid method of preparing plasma membranes from isolated fat cells is described. After homogenization of the cells, various fractions were isolated by differential centrifugation and linear gradients. Ficoll gradients were preferred because total preparation time was under 3 hr. The density of the plasma membranes was 1.14 in sucrose. The plasma membrane fraction was virtually uncontaminated by nuclei but contained 10% of the mitochondrial succinic dehydrogenase activity and 25–30% of the RNA and reduced nicotinamide adenine dinucleotide cytochrome c reductase activity of the microsomal fraction. Part of the RNA and NADH-cytochrome c reductase activity was believed to be native to the plasma membrane or to the attached endoplasmic reticulum membranes demonstrated by electron microscopy. The adenyl cyclase activity of the plasma membrane fraction was five times that of Rodbell's "ghost" preparation and retained sensitivity to epinephrine. The plasma membrane ATPase activity was five times that of the homogenate and microsomal fractions. Electron microscopic evidence suggested contamination of the plasma membrane fraction by other subcellular components to be less than the biochemical data indicated.

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