Studies on the preparation of rat liver plasma membrane fractions and on their polypeptide patterns

1978 ◽  
Vol 56 (7) ◽  
pp. 713-721 ◽  
Author(s):  
I. M. Yousef ◽  
R. K. Murray
Keyword(s):  
Plasma Membrane ◽  
Rat Liver ◽  
Membrane Fraction ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Canalicular Membrane ◽  
Polypeptide Patterns ◽  
Cell Plasma ◽  
Bile Canalicular Membrane ◽  
And Storage

Plasma membrane and bile canalicular membrane fractions were prepared from rat liver using NaHCO3, NaHCO3–CaCl2, and K2HPO4–KH2PO4 buffers (all at pH 7.4). The amount (expressed as milligrams protein per gram liver) of plasma membrane fraction exceeded the amount of bile canalicular membrane fraction using each of these three media; the use of NaHCO3–CaCl2 afforded a substantially higher yield of both types of membranes. The two membrane fractions exhibited complex patterns of polypeptides (> 30) on sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis. Several reproducible differences in polypeptide patterns were observable between the two membrane fractions; in particular, components possibly corresponding to the heavy chain of myosin and to actin were prominent in the bile canalicular membrane fraction. The effects of incubation in the above three buffers and in Tris–HCl (pH 7.4) on the polypeptide patterns of both types of membrane were studied. Many polypeptides were released from each type of membrane in all of these media. Differential effects on the polypeptide patterns of either type of membrane fraction were observed among the various buffers. In terms of minimizing loss of polypeptides, in general, NaHCO3–CaCl2 appeared to be the best buffer and Tris–HCl the worst buffer. The significance of these results for the preparation and storage of liver cell plasma membrane fractions is briefly discussed.

Liver Cell Plasma Membrane Lipids and the Origin of Biliary Phospholipid

1975 ◽  
Vol 53 (9) ◽  
pp. 989-997 ◽  
Author(s):  
I. M. Yousef ◽  
D. L. Bloxam ◽  
M. J. Phillips ◽  
M. M. Fisher
Keyword(s):  
Plasma Membrane ◽  
Liver Cell ◽  
Membrane Fraction ◽  
Plasma Membranes ◽  
Specific Activity ◽  
Phospholipid Composition ◽  
Bile Canaliculi ◽  
Canalicular Membrane ◽  
Cell Plasma ◽  
Bile Canalicular Membrane

The liver cell plasma membranes of fed male Wistar rats were separated into a fraction rich in bile canaliculi and the remainder of the plasma membrane. Electron-microscopically, the bile canalicular fraction consisted almost exclusively of intact bile canaliculi with their contiguous membranes. The remaining plasma membrane fraction consisted primarily of vesicles and sheets of membranes essentially free from bile canaliculi. The bile canalicular membrane fraction contained relatively more total lipid, cholesterol, and phospholipid, and relatively less protein. Although the phospholipid composition of the two fractions was the same, the specific activity of the bile canalicular membrane phospholipids, up to 12 h following in vivo administration of [2-3H]glycerol, was always significantly greater than that of the remaining plasma membranes, and showed a biphasic response not found in the latter. The specific activity of the phosphatidylcholine, phosphatidylethanolamine and lysophosphatidylcholine of the bile canalicular membranes rose to a peak within 40 min after administration of the label, fell sharply and then rose to a second peak after 120 min. The specific activity of the sphingomyelin and phosphatidylserine plus phosphatidylinositol of the bile canalicular membranes and of all the phospholipids of the remaining plasma membranes did not show the biphasic pattern but increased steadily to reach a maximum at 120 min. The specific activity of biliary phosphatidylcholine followed a pattern identical to that of the phosphatidylcholine, phosphatidylethanolamine and lysophosphatidylcholine of the bile canalicular membrane fraction. These results show that the average rate of turnover of phospholipid in the bile canalicular membranes is considerably greater than that in the remaining plasma membrane and other cell membrane fractions; they indicate that the phospholipid of the bile canalicular membranes exists in two or more pools, turning over at different rates; and they support the concept that biliary phospholipid is derived from the bile canalicular membrane. The results also suggest that bile canalicular phospholipid may be derived from two different sources, in contrast to the remaining plasma membrane.

scholarly journals Preparation and characterization of plasma membrane-enriched fractions from rat pancreatic islets.

1976 ◽  
Vol 71 (2) ◽  
pp. 606-623 ◽  
Author(s):  
A Lernmark ◽  
A Nathans ◽  
D F Steiner
Keyword(s):  
Plasma Membrane ◽  
Wheat Germ Agglutinin ◽  
Membrane Fraction ◽  
Wheat Germ ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Plasma Membrane Fraction ◽  
Fresh Plasma ◽  
Rat Islets Of Langerhans ◽  
Membrane Components

Methods have been developed for the isolation on a semi-micro scale of a plasma membrane-enriched fraction from rat islets of Langerhans. An important feature of these experiments is the use of 125I-labeled wheat germ agglutinin as a specific probe for plasma membrane-containing fractions. The partly purified plasma membrane fraction had a density in sucrose of about 1.10 and was enriched in the activities of 5'-nucleotidase, alkaline phosphatase, sodium-potassium, and magnesium-dependent ATPase and adenylate cyclase. It contained only very low levels of acid phosphatase, cytochrome c oxidase, insulin, and RNA. Further purification was hampered by the relatively small amounts of fresh plasma membrane material that could be obtained from 16-24 rats in each experiment. When islets were prelabeled with radioactive fucose, the plasma membrane-enriched fraction contained radioactivity at a four- to fivefold higher specific acivity than the whole islet homogenate. Sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis of plasma membrane-enriched fractions pooled from several experiments revealed a distinctive pattern of protein bands as compared with other less pure fractions. With respect to rapidity, apparent specificity, and easy reversibility of the labeling of the plasma membrane fraction, 125I-wheat germ agglutinin provides a highly useful tool for the detection of microgram quantities of plasma membrane components which should be applicable to many other systems as well.

scholarly journals Albumin associated with purified pig lymphocyte plasma membrane

1980 ◽  
Vol 192 (1) ◽  
pp. 49-57 ◽  
Author(s):  
M J Owen ◽  
B H Barber ◽  
R A Faulkes ◽  
M J Crumpton
Keyword(s):  
Plasma Membrane ◽  
Serum Albumin ◽  
Sodium Dodecyl Sulphate ◽  
Gel Electrophoresis ◽  
Membrane Fraction ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Reducing Conditions ◽  
Isoelectric Points ◽  
Pig Serum

Plasma-membrane preparations purified from pig lymphocytes contained a major polypeptide component of mol.wt. about 68 000. This component was identified as pig albumin by the following comparisons with authentic pig serum albumin: (a) co-migration when analysed by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis under reducing and non-reducing conditions; (b) identical isoelectric points; (c) similar “fingerprints” of arginine-containing tryptic peptides; (d) reactivity with anti-(pig albumin) serum. The albumin was bound tightly to the plasma membrane. Biosynthetic labelling of pig lymphocytes under a variety of conditions failed to provide evidence that albumin was synthesized by lymphocytes, suggesting that the plasma-membrane-associated albumin was of extraneous origin. Radiolabelled pig serum albumin, however, failed to bind to the plasma-membrane fraction when added before cell disruption. Although lymphocyte plasma membrane preparations from other species possessed a polypeptide of about 68 000 mol.wt., this was judged not to be albumin on the basis of electrophoretic mobility under non-reducing conditions; also, no polypeptide was precipitated by anti-albumin sera. It is concluded that pig lymphocyte plasma-membrane preparations possess albumin which, although firmly attached, was probably of extraneous origin. This association appeared not to be common to lymphocytes from other species.

Comparison of plasma membrane FABP and mitochondrial isoform of aspartate aminotransferase from rat liver

1993 ◽  
Vol 265 (5) ◽  
pp. G894-G902 ◽  
Author(s):  
D. D. Stump ◽  
S. L. Zhou ◽  
P. D. Berk
Keyword(s):  
Plasma Membrane ◽  
Fatty Acid ◽  
Amino Acid ◽  
Rat Liver ◽  
Aspartate Aminotransferase ◽  
High Performance ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Fatty Acid Binding ◽  
Sds Page

A relationship between plasma membrane fatty acid binding protein (FABPpm), a putative membrane transporter for long-chain fatty acids, and the mitochondrial isoform of aspartate aminotransferase (m-AspAT) has been reported. Accordingly, we have compared the chemical and immunological properties of rat liver m-AspAT with those of rat liver FABPpm isolated by two procedures: 1) detergent solubilization of the membranes followed by purification via fatty acid affinity chromatography (FABP-1) or 2) salt extraction of the membranes and subsequent purification by high-performance liquid chromatography (HPLC; FABP-2). Comparison of the three protein preparations revealed no differences with respect to NH2-terminal amino acid sequence, amino acid composition, peptides from tryptic digests, AspAT enzymatic activity, isoelectric point, mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), retention on five different HPLC columns, and immunoprecipitation and immunoblotting of SDS-PAGE separated proteins with polyclonal antisera. Examination of the proteins by nondenaturing PAGE showed a consistent second band in FABP-1 and FABP-2 not always present in m-AspAT. However, whenever present, this band was immunoreactive with antibodies to both m-AspAT and FABP-1. Hence, FABP-1 and FABP-2 are indistinguishable from one another. They are also at least closely related, if not identical, to m-AspAT.

scholarly journals Properties of the membrane proteins of rat liver lysosomes. The majority of lysosomal membrane proteins are exposed to the cytoplasm

1978 ◽  
Vol 176 (1) ◽  
pp. 75-82 ◽  
Author(s):  
D L Schneider ◽  
J Burnside ◽  
F R Gorga ◽  
C J Nettleton
Keyword(s):  
Membrane Proteins ◽  
Rat Liver ◽  
Membrane Fraction ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Thiol Groups ◽  
Liver Lysosomes ◽  
Lysosomal Membrane Proteins ◽  
Rat Liver Lysosomes ◽  
Lysosomal Protein

Rat liver lysosomes were lysed and subfractionated by differential centrifugation through 0.2M-NaCl to yield a membranous pellet. This membrane fraction contains less than 20% of the lysosomal protein, adenosine triphosphatase activity of about 1.2mumol/min per mg of protein, 120nmol of thiol groups/mg of protein and at least 16 protein and glycoprotein bands on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. The gel patterns of membranes isolated from lysosomes after treatment with (1) [125I]iodidehydrogen peroxide-lactoperoxidase, (2) toluene 2,4-di-isocyanate-activated bovine serum albumin, (3) trypsin and (4) subtilisin indicate that most of the membrane proteins are exposed to the cytoplasm. These exposed proteins are candidates for intracellular receptors which recognize either substances that are to be degraded or vesicles containing those substances.

scholarly journals Studies on rat liver plasma membrane. Altered protein and phospholipid metabolism after injection of d-galactosamine

1977 ◽  
Vol 166 (3) ◽  
pp. 455-462 ◽  
Author(s):  
W Bachmann ◽  
E Harms ◽  
B Hassels ◽  
H Henninger ◽  
W Reuitter
Keyword(s):  
Plasma Membrane ◽  
Rat Liver ◽  
Plasma Membranes ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Protein Composition ◽  
Phospholipid Metabolism ◽  
Morphological Alterations ◽  
Galactosamine Hepatitis

1. The metabolism of protein and phospholipid in rat liver plasma membranes isolated by the method of Neville [(1960) J. Biophys. Biochem. Cytol. 8, 413-422] was investigated 3 and 6 h after the injection of D-galactosamine in vivo. During this time, all the biochemical and morphological alterations associated with hepatitis developed. 2. After the injection of D-galactosamine the concentration of sphingomyelin in the plasma membrane decreased to below 60% of the control values. 3. The activity of 5′-nucleotidase (EC 3.1.3.5), which has been purified as a sphingomyelin-protein complex, decreased in the total homogenate as well as in the plasma-membrane fraction of livers of rats treated with galactosamine, to about 60% of the control values. 4. Protein synthesis, as measured by the incorporation of [14C]leucine into plasma membranes, was decreased to 45% of that of the controls. However, only small differences were observed in the amino acid composition of the plasma membrane after D-galactosamine treatment. 5. The protein composition of the plasma membranes was determined by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. The results showed a change from low- to high-molecular-weight proteins after the injection of galactosamine. 6. These results demonstrate different metabolic processes of the plasma membrane altered during the induction of galactosamine hepatitis.

scholarly journals Interactions between platelet-surface glycoproteins. Identification of glycoproteins capable of binding to platelet surfaces

1982 ◽  
Vol 202 (3) ◽  
pp. 707-716 ◽  
Author(s):  
D J Bowles ◽  
C Brunton
Keyword(s):  
Plasma Membrane ◽  
Sodium Dodecyl Sulphate ◽  
Gel Electrophoresis ◽  
Membrane Fraction ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Galactose Oxidase ◽  
Peanut Agglutinin ◽  
Platelet Surface ◽  
Lentil Lectin

1. Platelets have been isolated from plasma and their surface glycoconjugates radioactively-labelled using galactose oxidase and NaB3H4. 2. Conditions have been defined for optimal labelling of glycoproteins and a membrane fraction enriched in plasma membrane has been prepared and characterized by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. 3. Desialylated glycoproteins that act as receptors to peanut agglutinin and lentil lectin have been purified from a detergent extract of plasma membrane. 4. Two glycosylated polypeptides that are able to bind to the surfaces of platelets have been identified and some characteristics of the binding have been investigated.

Purification and partial characterization of cysteine-glutamate transaminase from rat liver

1977 ◽  
Vol 55 (9) ◽  
pp. 958-964 ◽  
Author(s):  
M. P. C. Ip ◽  
R. J. Thibert ◽  
D. E. Schmidt Jr.
Keyword(s):  
Molecular Weight ◽  
Rat Liver ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Liver Homogenate ◽  
Polyacrylamide Gel ◽  
Gel Chromatography ◽  
Labile Hydrogen ◽  
Apparent Homogeneity

Cysteine-glutamate transaminase (cysteine aminotransferase; EC 2.6.1.3) has been purified 149-fold to an apparent homogeneity giving a specific activity of 2.09 IU per milligram of protein with an overall yield of 15%. The isolation procedures involve the preliminary separation of a crude rat liver homogenate which was submitted sequentially to ammonium sulfate fractionation, TEAE-cellulose column chromatography, ultrafiltration, and isoelectrofocusing. The final product was homogenous when examined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS). A minimal molecular weight of 83 500 was determined by Sephadex gel chromatography. The molecular weight as estimated by polyacrylamide gel electrophoresis in the presence of SDS was 84 000. The purified enzyme exhibited a pH optimum at 8.2 with cysteine and α-ketoglutarate as substrates. The enzyme is inactivated slowly when kept frozen and is completely inactivated if left at room temperature for 1 h. The enzyme does not catalyze the transamination of α-methyl-DL-cysteine, which, when present to a final concentration of 10 mM, exhibits a 23.2% inhibition of transamination of 30 mM of cysteine. The mechanism apparently resembles that of aspartate-glutamate transaminase (EC 2.6.1.1) in which the presence of a labile hydrogen on the alpha-carbon in the substrate is one of the strict requirements.

Identification and characterization of cDNA clones encoding two homologous proteins that are part of the asialoglycoprotein receptor

1987 ◽  
Vol 7 (5) ◽  
pp. 1841-1847
Author(s):  
M McPhaul ◽  
P Berg
Keyword(s):  
Rat Liver ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Asialoglycoprotein Receptor ◽  
Cdna Clones ◽  
Differential Splicing ◽  
Homologous Proteins ◽  
Different Types ◽  
Identification And Characterization

The asialoglycoprotein receptor (ASGP-R) from rat liver contains the following three distinct protein species when it is analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis: RHL1 (42 kilodaltons), RHL2 (49 kilodaltons), and RHL3 (54 kilodaltons). In this paper we describe the isolation of cDNA clones encoding RHL1 and RHL2 from a cDNA library constructed from rat liver mRNA. A comparison of the predicted coding sequence for RHL2 with that for RHL1 showed that these sequences are highly homologous. The library also contained numerous cDNA clones for both RHL1 and RHL2 that were derived from unspliced precursor mRNAs. Differential splicing at the 5' end of the RHL1 transcript was inferred from the finding that two different types of RHL1 cDNA were identified, each having a different 5' terminus.

scholarly journals Influence of Pasteurization and Storage on Dynamic In Vitro Gastric Digestion of Milk Proteins: Quantitative Insights Based on Peptidomics

Foods ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 998 ◽  
Author(s):  
Xing Li ◽  
Yuxiang Gu ◽  
Shudong He ◽  
Olayemi Eyituoyo Dudu ◽  
Qiming Li ◽  
...  
Keyword(s):  
Cold Storage ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Milk Proteins ◽  
Hydrolysis Rate ◽  
Gastric Digestion ◽  
Pasteurized Milk ◽  
The Impact ◽  
And Storage

It is important to evaluate the nutritional quality of milk during the shelf-life, especially during home storage, from a consumer viewpoint. In this study, we investigated the impact of pasteurization (85 °C/15 s) and subsequent storage (at 4 °C for 7 days) on the coagulation behavior of milk and protein digestibility in a dynamic in vitro gastric digestion test. A high level of hydration in curd formed in pasteurized milk upon 7-day cold storage compared to raw and pasteurized milk, indicating fast pepsin diffusion in the interior of curds, increasing the hydrolysis rate. The digesta collected at various time points throughout the gastric digestion were studied using o-phthaldialdehyde (OPA), sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), liquid chromatography tandem mass spectrometry (LC-MS/MS), and amino acid analysis. These results showed that milk proteins were hydrolyzed quickly upon a long period of cold storage. Additionally, qualitative and quantitative results obtained using LC-MS/MS exhibited significant differences between samples, especially in pasteurized milk upon cold storage. Processing and storage played a decisive role in bioactive peptide generation. Such knowledge could provide insights into and directions for the storage of pasteurized milk for further clinical studies on protein bioavailability and the generation of bioactive peptides for desired health outcomes.

Sign in / Sign up

Export Citation Format

Share Document