scholarly journals The structure of the hepatic insulin receptor and insulin binding

1986 ◽  
Vol 239 (1) ◽  
pp. 127-133 ◽  
Author(s):  
F J Haynes ◽  
E Helmerhorst ◽  
C C Yip
Keyword(s):  
Insulin Receptor ◽  
Gel Electrophoresis ◽  
Plasma Membranes ◽  
Polyacrylamide Gel Electrophoresis ◽  
Insulin Binding ◽  
Intact Cells ◽  
Collagenase Treatment ◽  
Receptor Component ◽  
Predominant Band ◽  
Cytoplasmic Side

Hepatocytes or hepatic plasma membranes were photoaffinity-labelled with radioiodinated N epsilon B29-monoazidobenzoyl-insulin. Analysis of the samples by SDS/polyacrylamide-gel electrophoresis and autoradiography revealed the insulin receptor as a predominant band of 450 kDa. When hepatic plasma membranes were first treated with clostridial collagenase and then photolabelled, the insulin receptor appeared as a predominant band of 360 kDa. This effect of collagenase treatment on the insulin receptor was due to Ca2+-dependent heat-labile proteinases contaminating the preparation of collagenase, and it could be mimicked by elastase. The decrease in size of the insulin receptor to 360 kDa resulted from the loss of a receptor component that was inaccessible to photolabelling. In contrast, the size of the insulin receptor of intact cells was not affected by collagenase treatment. This suggests that the site sensitive to proteolysis was located on the cytoplasmic side of the plasma membrane. In hepatic plasma membranes that were treated with collagenase or elastase, and contained the 360 kDa form of the insulin receptor, the binding affinity for insulin was increased by up to 2-fold. These findings support the concept that a component which is either a part of, or closely associated with, the insulin receptor may regulate its affinity for insulin.

Adipocyte insulin-binding species: the 40 Å Stoke's radius protein

1984 ◽  
Vol 62 (7) ◽  
pp. 566-570
Author(s):  
C. Elliott ◽  
H. Joseph Goren
Keyword(s):  
Insulin Receptor ◽  
Gel Electrophoresis ◽  
Plasma Membranes ◽  
Insulin Receptors ◽  
Insulin Binding ◽  
Relative Mass ◽  
Single Polypeptide Chain ◽  
Dodecyl Sulfate ◽  
Single Polypeptide ◽  
Adipocyte Plasma Membranes

Several laboratories have demonstrated the presence of large (70 Å) (1 Å = 0.1 nm) and small (40 Å) insulin receptors. This report provides evidence that the 40 Å insulin receptor migrates on dodecyl sulfate – acrylamide gel electrophoresis as a 90 000 dalton protein and that this protein is a single polypeptide chain. 125I-labeled insulin was bound to plasma membranes from isolated rat adipocytes. Following removal of unbound 125I-labeled insulin, the mixture was exposed to disuccinimidyl suberate. Proteins tagged with 125I-labeled insulin were separated by dodecyl sulfate gel electrophoresis or Sepharose 6B chromatography. Autoradiography of the gels demonstrated several large (relative mass (Mr) > 300 000) and one small (Mr ~ 90 000) labeled protein in nonreduced membrane proteins. Dithiothreitol reduction decreased the large insulin-binding species to its known subunits, but the 90 000 dalton protein did not decrease in size. Triton X-100 solubilized plasma membranes were separated by Sepharose 6B chromatography. One labeled protein, with Kav = 0.57 elution position, on dodecyl sulfate gel electrophoresis migrated as a 90 000 dalton protein. Thus, rat adipocyte plasma membranes contain both an oligomeric insulin-binding species and a monomeric insulin-binding species. The relationship of the monomeric to the oligomeric insulin receptor is discussed.

scholarly journals Photoaffinity labelling of a nitrobenzylthioinosine-binding polypeptide from cultured Novikoff hepatoma cells

1986 ◽  
Vol 236 (3) ◽  
pp. 665-670 ◽  
Author(s):  
W P Gati ◽  
J A Belt ◽  
E S Jakobs ◽  
J D Young ◽  
S M Jarvis ◽  
...  
Keyword(s):  
Gel Electrophoresis ◽  
Plasma Membranes ◽  
Specific Binding ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Hepatoma Cells ◽  
Nucleoside Transport ◽  
Facilitated Diffusion ◽  
Animal Cells ◽  
Novikoff Hepatoma

Site-specific binding of nitrobenzylthioinosine (NBMPR) to plasma membranes of some animal cells results in the inhibition of the facilitated diffusion of nucleosides. The present study showed that nucleoside transport in Novikoff UA rat hepatoma cells is insensitive to site-saturating concentrations of NBMPR. Equilibrium binding experiments demonstrated the presence of high-affinity sites for NBMPR in a membrane-enriched fraction from these cells. In the presence of uridine or dipyridamole, specific binding of NBMPR at these sites was inhibited. When Novikoff UA membranes were covalently labelled with [3H]NBMPR by using photoaffinity techniques, specifically bound radioactivity was incorporated exclusively into a polypeptide(s) with an apparent Mr of 72,000-80,000, determined by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. Covalent labelling of this polypeptide was abolished in the presence of excess nitrobenzylthioguanosine (NBTGR) and reduced in the presence of adenosine, uridine or dipyridamole. The apparent Mr of the NBMPR-binding polypeptide in Novikoff UA cells is significantly higher than that reported for corresponding polypeptides in other cell types (Mr 45,000-66,000). When membrane-enriched preparations from S49 mouse lymphoma cells were photolabelled and mixed with labelled NovikoffUA membrane-enriched preparations, gel electrophoresis resolved the NBMPR-binding polypeptides from the two preparations.

Characterization of PIG Platelet Granule Proteins

1979 ◽  
Author(s):  
M.H. Fukami ◽  
J.L. Daniel ◽  
J.S. Bauer
Keyword(s):  
Gel Electrophoresis ◽  
Plasma Membranes ◽  
Polyacrylamide Gel Electrophoresis ◽  
Dense Granule ◽  
Release Mechanism ◽  
Molecular Weights ◽  
Dense Granules ◽  
Coomassie Blue ◽  
Pas Staining

Platelet granules contain glycoproteins similar to those found in platelet membranes (Hagen et al , BBA , 445, 21 4 , 1 976 ). Pig platelet granule fractions enriched in mitochondria, α-granules or dense granules were analyzed by SDS Polyacrylamide gel electrophoresis to determine if there are differences among the organelles. In a reduced system (5Ϊ OTT) the proteins of the ï-granules and dense granules showed staining patterns with Coomassie blue that were distinctly different from whole platelets, isolated membranes or mitochondria. In the granules about 10 to 12 bands with less mobility than actin were visualized. Staining with PAS was obtained in bands with apparent molecular weights of 250, 225, 185, 170, 150, 120, 55, 4B and 40 K. The 185 K band appeared to be the same as “thrombin sensitive protein”. The mobility of the 55 and 48 K hands were identical with the B (B) and γ-bands of bovine fibrinogen. The PAS staining of the granule components was more intense than that of whole platelets for the same amount of protein, indicating that granule membranes may be as rich in glycoproteins as external plasma membranes. With both PAS and Coomassie blue, the a-granule and dense granule staining patterns were almost identical. This observation may be relevant to recent studies which showed that both granule types exhibited similar release characteristics, suggesting that they share a common release mechanism. NIH-JSPHS Grant No. 14217

Phosphatidylglycerol and ß-Carotene Bound onto the D 1-Core Peptide of Photosystem II in the Filamentous Cyanobacterium

1994 ◽  
Vol 49 (1-2) ◽  
pp. 115-124 ◽  
Author(s):  
O. Kruse ◽  
A. Radunz ◽  
G. H. Schmid
Keyword(s):  
Fatty Acid ◽  
Photosystem Ii ◽  
Gel Electrophoresis ◽  
Lipid Analysis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Acid Mixture ◽  
Hexadecenoic Acid ◽  
Filamentous Cyanobacterium ◽  
Intact Cells ◽  
Oscillatoria Chalybea

Photosystem II-particles from the cyanobacterium Oscillatoria chalybea were isolated by fractionating centrifugation. Purification of these particles was achieved by a 22 hours centrifugation over a linear sucrose density gradient at 217.500xg. The obtained particle fraction exhibited an oxygen evolution activity which corresponded to three times the rate of intact cells and to five times the rate of intact thylakoids. The chlorophyll protein ratio was 1:10 and the ratio manganese/chlorophyll 1:34. SDS-polyacrylamide gel electrophoresis showed that the photosystem Il-fraction is composed of the core peptides D1 and D2, the chlorophyll-binding peptides CP 43 and CP 47, the extrinsic 33 kDa peptide (manganese stabilizing peptide, MSP) and phycobiliproteins with molecular masses between 16 to 20 kDa. Cyt b559 was not detected in our gel electrophoresis assay. Part of the peptides of the 30 kDa-region (D1, D2, MSP) occurred as aggregates with a molecular mass of 60 to 66 kDa. The D 1-peptide was isolated from the PS Il-preparation by SDS-gel electrophoresis. The intrinisic peptide reacts in the Western blot procedure with the antiserum to phosphatidylglycerol and with the antiserum to β-carotene. Incubation of the peptide with the antisera to monogalactosyldiglyceride, sulfoquinovosyldiglyceride and zeaxanthine resulted negatively. The binding of phosphatidylglycerol onto the D 1-peptide was confirmed by lipid analysis in HPLC and fatty acid analysis by gas chromatography. Only this lipid, respectively the typical fatty acid mixture of this lipid was detected. The lipid is characterized by the fact that the hexadecenoic acid does not exhibit trans-configuration, as is true for phosphatidylglycerol of higher plants and algae, but occurs in cis-configuration. With the antibody being directed towards the glycerol-phosphate residue and not towards the fatty acids, it can be concluded from the reaction of the antibodies with the bound lipid that the lipid is bound to the peptide via the fatty acid. The negatively charged phosphatidylglycerol increases the hydrophobicity of the peptide and leads to a negatively charged surface favouring binding of cations like calcium and magnesium. The fact that incubation of this PS Il-fraction with phospholipase inhibits photosynthetic activity by 25% which can be fully restored by addition of phosphatidylglycerol, shows that bound phosphatidylglycerol has a functional role.

scholarly journals Insulin receptor function is inhibited by guanosine 5′-[γ-thio]triphosphate (GTP[S])

1990 ◽  
Vol 270 (2) ◽  
pp. 401-407 ◽  
Author(s):  
H W Davis ◽  
J M McDonald
Keyword(s):  
Insulin Receptor ◽  
G Proteins ◽  
Plasma Membranes ◽  
Insulin Receptors ◽  
Insulin Binding ◽  
Peptide Sequence ◽  
Receptor Kinase ◽  
Receptor Function ◽  
Gtp Binding ◽  
Insulin Receptor Kinase

The regulatory role of GTP-binding proteins (G-proteins) in insulin receptor function was investigated using isolated insulin receptors and plasma membranes from rat adipocytes. Treatment of isolated insulin receptors with 1 mM-guanosine 5′-[gamma-thio]triphosphate (GTP[S]) inhibited insulin-stimulated phosphorylation of the beta-subunit, histone Hf2b and poly(GluNa4,Tyr1) by 22%, 65% and 65% respectively. Phosphorylation of calmodulin by the insulin receptor kinase was also inhibited by 1 mM-GTP[S] both in the absence (by 88%) and in the presence (by 81%) of insulin. In the absence of insulin, 1 mM-GTP had the same effect on calmodulin phosphorylation as 1 mM-GTP[S]. However, when insulin was present, GTP was less effective than GTP[S] (41% versus 81% inhibition). Concentrations of GTP[S] greater than 250 microM are necessary to inhibit phosphorylation. Although these concentrations are relatively high, the effect of GTP[S] is not due to competition with [32P]ATP for the insulin receptor kinase since (1) other nucleotide triphosphates did not inhibit phosphorylation as much as did GTP[S] (or GTP) and (2) the Vmax of the ATP-dependent kinase reaction was decreased in the presence of GTP[S]. GTP[S] (1 mM) also inhibited insulin binding to isolated receptors and plasma membranes, by 80% and 50% respectively. Finally, an antibody raised to a peptide sequence common to the alpha-subunits of G-proteins Gs, Gi, Go and transducin detected G-proteins in plasma membranes but failed to detect them in the insulin receptor preparation. These results indicate that GTP inhibits insulin receptor function, but does so through a mechanism that does not require a conventional GTP-binding protein.

Structural characteristics of growth hormone receptors on mouse 3T3 cells having different biological responses to growth hormone

1989 ◽  
Vol 3 (3) ◽  
pp. 239-245 ◽  
Author(s):  
E. Uchida ◽  
T. Hayakawa ◽  
S. Niimi ◽  
A. Tanaka ◽  
M. Morikawa
Keyword(s):  
Growth Hormone ◽  
Gel Electrophoresis ◽  
Structural Characteristics ◽  
Polyacrylamide Gel Electrophoresis ◽  
Cell Type ◽  
3T3 Cells ◽  
Intact Cells ◽  
Receptor Complexes ◽  
Gh Receptor ◽  
Adipose Conversion

ABSTRACT Cultured 3T3-F442A preadipocytes are able to undergo GH-promoted differentiation into adipocytes. The relationship between the structure and function of GH receptors on 3T3 cells (3T3-F442A preadipocytes, differentiated adipocytes and 3T3-C2 cells, which vary in susceptibility to adipose conversion or with respect to carbohydrate and lipid metabolism) was studied by the covalent cross-linking of 125I-labelled human (h) GH to intact cells with the bifunctional reagent disuccinimidyl suberate. When preadipocytes were cross-linked and analysed using sodium dodecylsulphate-polyacrylamide gel electrophoresis, a prominent 125I-labelled hGH-receptor complex of Mr 130 000 was observed along with minor complexes (Mr 300 000, 230 000 and 60 000) on autoradiography. Non-reducing—reducing two-dimensional gel electrophoresis revealed that the higher molecular weight complexes also contained the Mr 130 000 complex. Neuraminidase and tunicamycin treatment demonstrated that the GH receptor on F442A preadipocytes is a sialo-glycoprotein with N-linked carbohydrate chains. When the differentiated 3T3-F442A adipocytes and 3T3-C2 cells (a sub-line with no susceptibility to adipose conversion with GH) were examined in the same way as 3T3-F442A preadipocytes, no differences were observed in the specificity of GH binding and in the molecular size of the 125I-labelled hGH-receptor complexes and their glycosylation characteristics. This suggests that the structural characteristics of the GH receptor are closely related in each cell type, but that the hormonal signals produced after GH binding to the receptor may cause different effects according to the cell type.

scholarly journals Calcium-dependence of insulin receptor phosphorylation

1983 ◽  
Vol 214 (2) ◽  
pp. 361-366 ◽  
Author(s):  
W E Plehwe ◽  
P F Williams ◽  
I D Caterson ◽  
L C Harrison ◽  
J R Turtle
Keyword(s):  
Membrane Protein ◽  
Insulin Receptor ◽  
Sodium Dodecyl Sulphate ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Beta Subunit ◽  
Receptor Phosphorylation ◽  
32P Incorporation ◽  
Isolated Rat

Phosphorylation of the insulin receptor of isolated rat adipocytes in response to insulin has been studied. Immunoprecipitation of adipocyte membrane protein demonstrated increased incorporation of 32P after exposure to insulin for 15 min, but this was dependent on the presence of physiological concentrations of Ca2+ and Mg2+. Autoradiography of solubilized immunoprecipitated membrane protein after sodium dodecyl sulphate/polyacrylamide-gel electrophoresis revealed that most of the 32P incorporation occurred in a band corresponding to Mr 95 000, which has been identified previously as the beta-subunit of the insulin receptor. 32P incorporation was inhibited by 2,4-dinitrophenol and trifluoperazine. It is suggested that insulin-receptor phosphorylation is an energy-requiring process that is Ca2+-dependent and may be modulated by calmodulin. Phosphorylation may proceed independently of glucose transport.

Effect of exercise on insulin receptor binding and kinase activity in skeletal muscle

1989 ◽  
Vol 256 (1) ◽  
pp. E138-E144 ◽  
Author(s):  
J. L. Treadway ◽  
D. E. James ◽  
E. Burcel ◽  
N. B. Ruderman
Keyword(s):  
Skeletal Muscle ◽  
Insulin Receptor ◽  
Insulin Action ◽  
White Muscle ◽  
Kinase Activity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Insulin Receptors ◽  
Insulin Binding ◽  
Similar Data

Insulin action in skeletal muscle is markedly enhanced for several hours after an acute bout of exercise. The purpose of this study was to examine the possible involvement of the intrinsic tyrosine kinase activity of the insulin receptor in mediating these effects. Red and white muscles were removed from rats either at rest or following a treadmill run (45 min at 18 m/min), and insulin receptors were isolated in partially purified form. Basal and insulin-stimulated receptor kinase activity was higher in red than in white muscle, in agreement with previous studies (J. Biol. Chem. 261: 14939-14944, 1986). There was no effect of exercise on insulin binding, basal and insulin-stimulated receptor autophosphorylation, or basal and insulin-stimulated exogenous kinase activity, in either red or white muscle. Similar data were obtained when phosphatase inhibitors were used during receptor isolation. The structure of insulin receptors isolated from the muscle of exercised and control rats was similar as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of affinity cross-linked insulin receptors. We conclude that enhanced insulin action in muscle during the postexercise state is not related to increased kinase activity of the insulin receptor.

D-Glucose uptake and insulin binding by the human adipose cell plasma membrane as a function of its polypeptide composition

1977 ◽  
Vol 55 (2) ◽  
pp. 126-133 ◽  
Author(s):  
Bluma G. Brenner ◽  
Shiro Ozaki ◽  
Norman Kalant ◽  
Arthur Kahlenberg
Keyword(s):  
Plasma Membrane ◽  
Glucose Uptake ◽  
Plasma Membranes ◽  
Binding Capacity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Insulin Binding ◽  
Partial Purification ◽  
Scatchard Analysis ◽  
Molecular Weight Range

A preparation of plasma membranes isolated from human omental lipocytes is composed of about 15 major polypeptide components including three major glycoproteins with an apparent molecular weight range from 100 000 to 23 000, as determined by sodium dodecyl sulfate – polyacrylamide gel electrophoresis. Extraction of this membrane preparation with sodium iodide or 2,3-dimethylmaleic anhydride solubilized 50 and 70% of the membrane protein, respectively, resulting from the extensive extraction of protein from all but two of the major membrane polypeptide components. This removal of protein did not affect the membrane's stereospecific D-glucose-uptake activity but did reduce its total specific [l25I]insulin-binding activity by 46–67%. The binding of [125I]insulin to its specific receptor on lipocyte plasma membranes was detected at physiologic concentrations of the hormone and could be competitively displaced by increasing concentrations of native insulin. The kinetic behaviour of this reaction was approximated by Scatchard analysis, and both the affinity and binding capacity of the plasma membrane for insulin were increased at lower temperatures.These results suggest that D-glucose transport in human adipose tissue is mediated by an intrinsic component of the hydrophobic structure of the lipocyte plasma membrane, and represent a partial purification of this component. In addition, these studies demonstrate and characterize the binding of insulin to the plasma membrane isolated from human lipocytes. A quantitative study of this binding reaction may provide further understanding of the mechanisms underlying the decreased insulin responsiveness characteristic of human diabetes.

Discriminating between Cell Surface and Intracellular Plasminogen-binding Proteins: Heterogeneity in Profibrinolytic Plasminogen-binding Proteins on Monocytoid Cells

2000 ◽  
Vol 84 (11) ◽  
pp. 882-890 ◽  
Author(s):  
Michael Green ◽  
Lindsey Miles ◽  
Stephen Hawley
Keyword(s):  
Cell Surface ◽  
Peripheral Blood ◽  
Gel Electrophoresis ◽  
Binding Proteins ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Annexin Ii ◽  
Two Dimensional ◽  
Intact Cells ◽  
Carboxyl Terminal

SummaryWhen plasminogen binds to cell surfaces, its activation is markedly enhanced compared to soluble plasminogen. Although several distinct molecules may contribute to plasminogen binding to a given cell type, the subset of plasminogen receptors responsible for enhancing plasminogen activation expose a carboxyl-terminal lysine on the cell surface and are sensitive to proteolysis by carboxypeptidase B (CpB). To distinguish this subset of plasminogen receptors from plasminogen-binding proteins that are not profibrinolytic, we treated intact U937 monocytoid cells and peripheral blood monocytes with CpB to remove exposed carboxyl-terminal lysines, and subjected the membrane proteins to two-dimensional gel electrophoresis followed by ligand blotting with 125I-plasminogen. Western blotting was performed with antibodies against previously characterized candidate plasminogen receptors to identify plasminogen-binding proteins on the two-dimensional ligand blots. Densitometry of autoradiograms of the 125I-plasminogen ligand blots of U937 cell membranes revealed that membraneassociated α-enolase, actin and annexin II showed minimal changes in 125I-plasminogen binding following CpB treatment of intact cells, suggesting that these proteins are not accessible to CpB on the U937 cell surface and most likely do not serve as profibrinolytic plasminogen receptors on U937 cells. In contrast, densitometry of autoradiograms of 125I-plasminogen ligand blots of monocyte membranes revealed that 125I-plasminogen binding to α-enolase was reduced 71% by treatment of intact cells with CpB, while binding to annexin II was reduced 14%. Thus, a portion of membrane-associated α-enolase and annexin II expose carboxyl terminal lysines that are accessible to CpB on the peripheral blood monocyte surface, suggesting that these molecules may serve as profibrinolytic plasminogen receptors on monocytes. Our data suggest that U937 cells and peripheral blood monocytes have distinct sets of molecules that constitute the population of cell surface profibrinolytic plasminogen-binding proteins. Furthermore, our data suggest that while several plasminogen-binding proteins with carboxyl terminal lysines are associated with cell membranes, only a small subset of these proteins expose a carboxyl terminal lysine that is accessible to CpB on the cell surface. The abbreviations used are: 2D, two-dimensional; 2D-PAGE, two-dimensional polyacrylamide gel electrophoresis; BSA, bovine serum albumin; CpB, carboxypeptidase B; EACA, є-aminocaproic acid; HBSS, Hanks’ Balanced Salt Solution supplemented with 20 mM HEPES; HBSS-BSA, HBSS with 0.1% bovine serum albumin; HRP, horseradish peroxidase; IEF, isoelectric focusing; PBS, phosphate buffered saline; PMSF, phenylmethylsulfonyl fluoride; PVDF, polyvinylidene difluoride; SDS, sodium dodecyl sulfate; SDSPAGE, sodium dodecyl sulfate polyacrylamide gel electrophoresis; TBST, Tris buffered saline with 0.1% Tween 20; uPAR, urokinase-type plasminogen activator receptor.

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