Solubilization and characterization of functionally coupled Escherichia coli heat-stable toxin receptors and particulate guanylate cyclase associated with the cytoskeleton compartment of intestinal membranes

• 1.1. Particulate guanylate cyclase and receptors for E. coli heat-stable enterotoxin were solubilized from the rat intestinal cytoskeletal compartment using Lubrol-PX and KC1.
• 2.2. Thirty to forty percent of the ST receptor and guanylate cyclase activities were extracted from the lipid layer with Lubrol-PX alone.
• 3.2. Seventy percent of the remaining activities were solubilized from the cytoskeleton with Lubrol-PX and KCl.
• 4.3. Guanylate cyclase solubilized from either compartment exhibited similar reaction kinetics.
• 5.4. Both high- and low-affinity classes of ST receptors were solubilized from the lipid and cytoskeleton compartments.
• 6.5. In the presence of ATPγS, ST selectively activated the guanylate cyclase solubilized from the cytoskeleton compared to that solubilized from the lipid bilayer.
• 7.6. Crosslinking experiments demonstrated a preferential solubilization of the 130 kDa receptor subunit from the cytoskeleton and the 56 kDa subunit from the lipid bilayer.
• 8.7. Development of a procedure to solubilize ST receptors and guanylate cyclase from the intestinal membrane cytoskeleton will permit purification and further detailed studies of the coupling of these activities.

     

A comparative study of seafish erythrocytes and agglutinins from seaweeds

• 1.1. To date, only a few authors have assayed the agglutinic activity of marine algae against fish erythrocytes, and in these cases, mainly against freshwater fish.
• 2.2. For the first time, the hemagglutinic activity of 70 seaweeds (29 brown, 37 red and four green algae) against erythrocytes of 16 seaflsh species is reported.
• 3.3. The presence of agglutinins was demonstrated in 100% of algae assayed, against at least one of the different types of erythrocytes tested.
• 4.4. The results obtained confirm the presence of receptors for algae agglutinins on the surface of the erythrocytes of the fish studied.
• 5.5. This could be useful in establishing the origins of fish populations, as these serological differences could distinguish between populations of cultivated and wild fish.

     

Biomines-stimulated phosphorylation and (Na+, K+-ATPase in the gills of the chinese crab,Eriocheir sinensis

• 1.1. Subcellular distribution of (NA⁺, K⁺-ATPase and ouabain-insensitive ATPase (Mg²⁺-ATPase) are compared in branchial tissues of the euryhaline crab, Eriocheir sinensis, acclimated to fresh water.
• 2.2. Both the anterior and posterior gills contain cAMP-dependent protein kinase and endogenous protein substrate for phosphorylation.
• 3.3. Phosphorylation occurs in both “particulate” and “soluble” subcellular fractions but its stimulation by cAMP is restricted to the “soluble” fraction.
• 4.4. serotonin (5-HT) and dopamine receptors are present only in the “light particulate” fraction isolated from the posterior gills.

• 1.(a) Serotonin and dopamine have no effect on the phosphorylation observed in a subcellular fraction alone.
• 2.(b) Activation of the phosphorylation by serotonin and dopamine is found when the soluble fraction (source of cAMP-dependent protein kinase) is added to the fraction P₃ from the posterior gills.
• 3.(c) No activation occurs with the fractions P₃ as well as P₁ or P₂ (not shown) from anterior gills of fresh water crab.
• 4.(d) Cyproheptadine, a serotonin receptor antagonist, inhibits the 5-HT dependent increase in phosphorylation.
• 5.(e) The dopamine receptor antagonist, chlorpromazine, inhibits dopamine-stimulated phosphorylation.
• 6.5. Ouabain mimics the effect of cyproheptadine on the serotonin-stimulated phosphorylation found in the posterior gills.

     

Internal reference standards in ionic regulation and the predictability of ionic concentrations in animals

• 1.1. The regulation of ions at similar concentrations in most individuals of a species suggests the existence of internal reference standards.
• 2.2. Few have been identified, but many probably relate to cell membrane properties, including potentials, surface charge densities and equilibrium constants of receptor molecules.
• 3.3. Solubility may sometimes determine the product [Ca²⁺][CO₃²⁻].
• 4.4. Reference standards must generally each relate to more than one ionic species.
• 5.5. For some concentrations, including osmolality, there may be no direct reference standard.

     

Distribution of beta-adrenergic binding in fractionated porcine adipocytes

• 1.1. The subcellular distribution of the porcine adipocyte beta-adrenergic receptor was studied in fractionated adipocytes.
• 2.2. The 30,000 g pellet obtained from hypotonically lysed cells contained membrane vesicles and mitochondria; it yielded approx 200–300 fmol dihydroalprenolol-bound receptors/mg protein.
• 3.3. Activity was increased to about 1000 fmol/mg protein after isolation of a plasma membrane fraction on a Percoll gradient.
• 4.4. The 5'-nucleotidase, succinate dehydrogenase and lactate dehydrogenase activities were usually enriched in compartments different from the ligand-binding activity.
• 5.5. Activity of porcine adipocyte 5'-nucleotidase, a purported plasma membrane marker enzyme, was not distributed in the same manner as the beta-adrenergic receptor.

     

Thermoreceptor distribution in different skin layers and its significance for thermoregulation

• 1.1.|The activity pattern of 50 cold receptors of the rabbit nose back skin was investigated.
• 2.2.|The latency of the response of individual cold receptors to identical cold stimuli varied between 0.8 ± 0.3 to 29.4 ± 4.5 s; maximal firing rates are attended after 5.5 ± 0.5 to 72.2 ± 6.2 s. Characteristic phasic responses are only demonstrated by short latency receptors.
• 3.3.|The results suggest that cold receptors are distributed throughout the skin of the rabbit's nose.
• 4.4.|Changes of temperature gradients between different skin layers were measured at different ambient temperatures.
• 5.5.|It is suggested that cold receptors might indicate heat flow through the skin.

     

Locust vitellogenin receptor: an acidic glycoprotein with N- and O-linked oligosaccharides

• 1.1. The locust vitellogenin (VTG) receptor which is embedded in oocyte plasma membranes is a glycoprotein.
• 2.2. With various lectins oligosaccharide units have been identified, among them neuraminic acid linked to Gal or GalNAc, mannose chains, Gal linked to GalNAc or GlcNAc and fucose linked to GlcNAc.
• 3.3. With specific enzymes it could be shown that mannose and most other oligosaccharides are O-linked while others like fucose are N-linked.
• 4.4. Enzymatic removal of all O-linked carbohydrates resulted in a drop of the molecular mass of the receptor protein from 200,000 to 110,000.
• 5.5. A total of N- and O-linked oligosaccharides of 54% was calculated.
• 6.6. The isoelectric point of the receptor was found to be at pH 3.4 increasing slightly after removal of neuraminic acid.
• 7.7. Removal of neuraminic acids destroyed the binding ability for VTG.

     

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Effect of bovine milk antigens and egg lysozyme on the binding of 59Fe-lactoferrin to platelet plasma membranes

• 1.1. Platelets bind specifically to lactoferrin. A significant similarity between human lactoferrin and some bovine milk proteins has been established.
• 2.2. Because of the structural homology of lactoferrin and cows milk proteins they are able to influence lactoferrins regulatory function on the level of its binding to membrane receptors on platelets.
• 3.3. An inhibitory effect of bovine α-lactalbumin and of β-lactoglobulin on lactoferrin-receptor interaction was shown.
• 4.4. Bovine α-lactalbumin competes with lactoferrin for the binding sites.
• 5.5. Scatchard plot analysis of data shows one binding site for lactoferrin in the presence of α-lactalbumin with an affinity constant, Ka = 0.46 × 10⁹ mol/1 and 335 receptors/cell.
• 6.6. The inhibitory effect of β-lactoglobulin reaches 62% and is different for the common fraction ⨿-lactoglobulin and the genetic variants β-lactoglobulin A and B.
• 7.7. β-lactoglobulin does not compete with lactoferrin for the membrane receptors.
• 8.8. Bovine casein and egg lysozyme stimulate ⁵⁹Fe-lactoferrin binding to the receptors. The mechanism of these effects is still unknown.
• 9.9. Tested alimentary antigens are able to interact with lactoferrin and also with some platelet membrane structures.
• 10.10. Established changes in lactoferrin binding to the platelet membrane might be in relation to lactoferrins regulatory function and (or) eliminating mechanisms of these alimentary antigens.

     

Alteration of 5-hydroxytryptophan-induced hypothermia by serotonergic agents in the adult domestic fowl (Gallus domesticus)

• 1.1.|5-Hydroxytryptophan (5-HTP) induced a dose-dependent hypothermia in adult fowls.
• 2.2.|The hypothermic effect of 5-HTP was potentiated by carbidopa, citalopram, additive with (±), (−) and (+) propanolol and antagonised by methysergide and metitepine.
• 3.3.|Cyproheptadine, xylamidine and ketanserin did not antagonised 5-HTP-induced hypothermia.
• 4.4.|The results suggest that the hypothermic effect of 5-HTP in fowls may be mediated mainly via activation of central 5-HT receptors, probably 5-HT₁ receptors.

     

A Platform for Extracellular Interactome Discovery Identifies Novel Functional Binding Partners for the Immune Receptors B7-H3/CD276 and PVR/CD155

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Highlights

• •New platform for high throughput detection of transient interactions between membrane proteins.
• •IL20RA is a receptor for the orphan checkpoint inhibitor B7-H3.
• •The natural killer cell protein KIR2DL5A binds the immune receptor PVR.
• •KIR2DL5 binding to PVR regulates natural killer cell cytotoxicity and inhibits tumor cell killing.
• •Elucidation of receptor interactomes to gain insights into extracellular protein biology.

     

In vivo photo-affinity labelling of glutathione receptors mediating the tentacle ball formation,a behavioral response associated with the feeding of Hydra

• 1.1. The tentacle ball formation, a response associated with the feeding of Hydra japonica, with S-(p-azidophenacyl)-glutathione (GSPAP) was reduced upon illumination.
• 2.2. GSPAP did not cause the depression without illumination nor did illumination without GSPAP.
• 3.3. The concentration dependence of the response of the photolabelled animals suggested high and low affinity glutathione receptors. The low affinity receptor may be efficiently tagged with GSPAP upon photolysis.

     

Activation and inhibition of insulin receptor autophosphorylation by trypsin treatment of intact H35 cells

• 1.1. Treatment of intact cultured H35 cells with trypsin (1 mg/ml) for 15 min at low temperature (4°C) or for 30 sec at 37°C causes activation of the insulin receptor subsequently isolated from the cells.
• 2.2. Receptor activation was assessed by increased phosphotyrosine content of the β-subunit of the receptor, and increased autophosphorylation using [³²P]-ATP.
• 3.3. Treatment of the cells for 15 min at 37°C however completely abolished insulin binding and all insulin receptor kinase activity.
• 4.4. These data demonstrate that proteolytic damage of the extracellular domain of the insulin receptor can render the receptor kinase inactive and lead to a cell which is unresponsive to insulin.

     

Phosphoinositide hydrolysis in Ki-ras-transformed fibroblasts stimulated by platelet-derived growth factor and bradykinin

• 1.1. Signal transduction in response to platelet-derived growth factor (PDGF)-BB and bradykinin (BK) have been examined by measuring inositol polyphosphate formation in NIH3T3 fibrobalst and v-Ki-ras -transformed NIH3T3 fibroblast (DT).
• 2.2. The PDGF-induced inositol polyphosphate formation in NIH3T3 was greater than that in DT cells, in which autophosphorylation of PDGF receptor and tyrosine phosphorylation of phospholipase C (PLC)-γ 1 were suppressed when examined by immunoblotting with anti-phosphotyrosine antibody.
• 3.3. On the other hand, BK-stimulation produced a much higher level of inositol polyphosphate in DT cells which have a greater number of BK receptors.
• 4.4. These results indicate that in Ki-ras transformed cells the decrease (caused by PDGF) and the increase (caused by BK) in phosphoinositide hydrolysis are due to the defective autophosphorylation of PDGF receptors leading to a reduction in PLC-γ 1 tyrosine phosphorylation and the overexpression of BK receptors, respectively.

     

Breast,hips, and buttocks revisited: Honest fatness for honest fitness

This paper comments on: Low, B. S., Alexander, R. D., and Noonan, K.M. Human hips, breast, and buttocks: Is fat deceptive? Ethology and Sociobiology 8: 249-247, 1987. In it I argue that:

• 1.1. Sexual selection has probably not been the most important selection pressure on
• 2.female human body shape.
• 3.2. Male humans in different cultures find different aspects of the female body attractive
• 4.and therefore are unlikely to have exerted consistent directional sexual selection on
• 5.the female body.
• 6.3. Breast size is not correlated with lactation success.
• 7.4. Visible hip width is not correlated with parturition success.
• 8.5. Women would lower their fitness if they tried to deceive men about their internal
• 9.pelvic dimensions.
• 10.6. There are many alternative hypothesis to explain the existence of fat onwomen's
• 11.breast, hips, and buttocks.

     

Salinity tolerance of adult and juvenile red king crabs Paralithodes camtschatica

• 1.1. Juvenile king crabs were more tolerant of reduced salinities than adult crab; juvenile crab were better volume regulators at reduced salinities than adult crab.
• 2.2. Adult female king crab hemolymph was hyperosmotic to full seawater (30 ppt) and isosmotic to dilute seawater. Juvenile king crab (2 years old) were hypoosmotic at the same concentrations.
• 3.3. Lower osmotic concentration of juvenile hemolymph is at least partially due to lower sodium concentration.
• 4.4. Juvenile king crab can tolerate some dilution and survive for short periods in the reduced salinity of the lower intertidal zone.

     

Analysis of steroid receptor domains with the aid of antihormones

• 1.1. The receptors for steroid hormones consist of well defined domains with overlapping functions.
• 2.2. Contrary to the classical view, it is now becoming increasingly evident that agonist binding regions of the ligand binding domain are not identical to those that bind steroid antagonists.
• 3.3. The DNA binding domain can be activated equally well in presence of both agonists and antagonists, again contradicting the classical view where only the physiologically active hormone was believed to induce such a change.
• 4.4. In some cases, a synthetic antagonist is a more specific ligand for the receptor than the natural hormone.
• 5.5. Synthetic antagonists are therefore important not only to alleviate disease in the human subject, they have also become an important tool to elucidate the mechanism of transactivation by steroid hormones.

     

Crayfish retinular cells: Influence of extracellular sodium and calcium upon receptor potential

• 1.1. In crayfish, light stimulation of the retinular cells induces a depolarizing receptor potential.
• 2.2. Experiments were designed to determine the role of Na⁺ and Ca²⁺ on receptor potential during dark And light states.
• 3.3. Depolarization depends on Na⁺ and Ca²⁺ availability to the retinular cell.
• 4.4. Repolarization velocity and response duration depend on extracellular Ca²⁺ availability.
• 5.5. Light adaptation increases receptor potential dependence on calcium and sodium ions.
• 6.6. We analyse these results with respect to other invertebrate photoreceptors.

     

Polymorphism and tissue specificity of scallop tropomyosin

• 1.1. Molecular polymorphism of tropomyosin from various muscle sources of the scallop, Patinopecten yessoensis, was investigated by electrophoretic and immunochemical methods.
• 2.2. Treatment of the muscle sources with trichloroacetic acid (TCA) prior to tropomyosin preparation was found useful to prevent proteolytic degradation of this protein.
• 3.3. Electrophoretic and immunochemical analysis revealed that at least six kinds of tropomyosin isoforms may exist in scallop muscle tissues.
• 4.4. The tropomyosin isoforms showed tissue-specific distribution in amounts and molecular species among the various muscle sources.

     

Preparation and characterization of biotinylated probes for the β-interferon receptor

• 1.1. Recently we described the isolation of the β-interferon receptor [Zhang et al. (1986) J. biol. Chem. 261, 8017–8021]. A highly purified product was obtained but in low quantities.
• 2.2. The use ofbiotinylated β-interferon as a ligand represents an alternate approach to receptor isolation.
• 3.3. We have prepared and characterized the derivatives N-(biotinyl)- and N-(biotinyl-ϵ-aminocaproyl)-recombinant human [Ser¹⁷-interferon β (B- and BC-recHulFNβ).
• 4.4. Biotin incorporation does not result in any loss of antiviral activity, demonstrating the recognition of the derivative by the cell receptor.
• 5.5. The biotinylated recHuIFNβ binds specifically and reversibly to succinoylavidin or guanidine thiocyanate-stripped succinoylavidin linked to a Sepharose matrix.
• 6.6. Comparison of the competition curves obtained with [¹⁴C]biotin and [³H]biotinyl recHuIFN, in the presence of increasing concentrations of biotin suggests that the IFN moiety of the derivative has little effect on the affinity of biotin for avidin.
• 7.7. Biotinylated recHuIFNβ derivatives represent useful probes for the β-IFN receptor.