摘要:

Protein phosphorylation is one of the most common mechanisms for controlling protein function. We now know that most phosphoproteins contain multiple phosphorylation sites and that these sites are often located in clusters. From the study of the enzyme glycogen synthase, one mechanism for the formation of phosphorylation clusters has been discovered that involves the concerted action of two or more protein kinases. One protein kinase, the primary kinase, introduces a phosphate group that is a requirement for the action of another, secondary, protein kinase. Thus the multiple phosphorylation occurs in a hierarchal fashion. This mechanism, which is critical for the phosphorylation of glycogen synthase, is likely to be a much more widespread phenomenon.— Roach, P. J. Control of glycogen synthase by hierarchal protein phosphorylation.FASEB J.4: 2961‐2968; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.12.2168324

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

Carotenoid pigments are an important component in the plumage of birds. The metabolic precursors are dietary in origin but many species have the capacity to chemically modify and selectively deposit the pigments. The ensuing plumage patterns are important in communication and identification. The bright yellows, oranges, and reds are due mostly to xanthophylls; keto and hydroxy carotenes. Some are deposited unmodified (e.g., lutein) whereas others are modified chemically (canthaxanthin, astaxanthin). Early workers concentrated on demonstrating that feather carotenoids were derived from the diet and deposited selectively. Progress in defining and solving biological problems depended on advances in chemical and analytical techniques. Subsequent investigation showed that various plumage colormorphs, seasonal plumage changes or colors in common mutant, were due to relatively simple chemical changes in carotenoids but had profound biological consequences. Equally important was the realization that many of these processes were under genetic control. Validation came from feeding studies of flamingos and finches. Recent studies have employed the plumage carotenoids to test hypotheses of genetic divergence, to relate plumage color to environmental process, and to demonstrate the influence of synthetic changes on color. Understanding the processes has advanced with the introduction of high‐resolution separation techniques and the ability to determine both conformation and absolute configuration. The next steps will be in the direction of understanding the enzymatic modification, transport, and tissue selectivity of feather carotenoids.— Brush, A. H. Metabolism of carotenoid pigments in birds.FASEB J.4: 2969‐2977; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.12.2394316

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

It was known in the 1950s that hepatic microsomal glucose‐6‐phosphatase plays an important role in the regulation of blood glucose levels. All attempts since then to purify a single polypeptide with glucose‐6‐phosphatase activity have failed. Until recently, virtually nothing was known about the molecular basis of glucose‐6‐phosphatase or its regulation. Recent studies of the type 1 glycogen storage diseases, which are human genetic deficiencies that result in impaired glucose‐6‐phosphatase activity, have greatly increased our understanding of glucose‐6‐phosphatase. Glucose‐6‐phosphatase has been shown to comprise at least five different polypeptides, the catalytic subunit of glucose‐6‐phosphatase with its active site situated in the lumen of the endoplasmic reticulum; a regulatory Ca2+binding protein; and three transport proteins, T1;T2, and T3, which respectively allow glucose‐6‐phosphate, phosphate, and glucose to cross the endoplasmic reticulum membrane. Purified glucose‐6‐phosphatase proteins, immunospecific antibodies, and improved assay techniques have led to the diagnosis of a variety of new type 1 glycogen storage diseases. Recent studies of the type 1 glycogen storage diseases have led to a much greater understanding of the role and regulation of each of the glucose‐6‐phosphatase proteins.— Burchell, A. Molecular pathology of glucose‐6‐phosphatase.FASEB J.4: 2978‐2988; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.12.2168325

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

Endothelins (ET) are a family of regulatory peptides synthesized by selected endothelial and epithelial cells that act in a paracrine fashion on nearby smooth muscle or connective tissue cells. We review the pathways of transmembrane signaling triggered by binding of endothelin peptides to receptors on the plasma membrane. Although our understanding of many components is unclear, endothelin peptides appear to evoke a phosphoinositide‐linked signaling system that bears a striking resemblance to signaling pathways activated by other regulatory peptides. Expression of endothelin receptors and specific pathways stimulated by activated receptors are controlled in a cell‐ and tissue‐specific manner, which perhaps explains the diverse biological actions of endothelin in different tissues. Complex negative feedback pathways regulate endothelin‐induced signaling at the receptor and second messenger levels. Moreover, by regulating the activity of sequence‐specific DNA binding proteins, short‐term signals by ET can be extended to long‐term effects involving gene expression. Regulation of gene expression by ET could account for complex events such as mitogenesis and vascular and tissue remodeling in disease.— Simonson, M. S.; Dunn, M. J. Cellular signaling by peptides of the endothelin gene family.FASEB J.4: 2989‐3000; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.12.2168326

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

A single photon can be detected by a rod photoreceptor cell. The absorption of light by rhodopsin triggers a cascade of reactions that amplifies the photon signal and results in ion channel closure with hyperpolarization of the rod photoreceptor cell. Light‐induced conformational changes in rhodopsin facilitate the binding of a guanosine nucleotide‐binding protein, transducin, which then undergoes aGTP‐GDP exchange reaction and dissociation of the transducin complex. A subunit of transducin then activates a phosphodiesterase complex that hydrolyzes cyclic GMP. In darkness, cyclic GMP binds to cation channels of the photoreceptor plasma membrane, maintaining them in an open configuration. The light‐induced reduction in cyclic GMP concentration dissociates the bound cyclic GMP, resulting in channel closure and hyperpolarization. Down‐regulation of the cascade involves other proteins that block the interaction of transducin with rhodopsin and another protein that may interfere with transducin recycling. Cone photoreceptors possess a light‐activated cascade that follows the rod format, but it is composed of proteins that are homologous to those of rod photoreceptors. Phototransduction in invertebrate photoreceptors uses rhodopsin to activate a cascade that uses phosphoinositides and calcium ion to regulate membrane polarization.— Lolley, R. N.; Lee, R. H. Cyclic GMP and photoreceptor function.FASEB J.4: 3001‐3008; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.12.1697545

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

The tartrate‐resistant acid phosphatases or purple acid phosphatases constitute a class of related mammalian enzymes. Spectroscopic and magnetic studies have revealed that the purple phosphatases contain a novel dinuclear iron active site that is responsible for the purple color. More biologically and biomedically oriented research has shown that the tartrate‐resistant acid phosphatases generally occur in osteoclasts and white blood cells, where they appear to be localized in lysosomes or similar organelles. Despite the different names given the enzymes by researchers in the two fields, recent sequence determinations and immunological studies indicate that the enzymes are identical. The status of research in both fields is reviewed in an attempt to present a unified picture of the structure, function, and mode of action of these unique metalloproteins.—Vincent, J. B.; Averill, B. A. Purple acid phosphatase and tartrate‐resistant acid phosphatase: an enzyme with a double identity.FASEB J.4: 3009‐3014; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.12.2394317

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

A peptide that inhibits egg development in mosquitoes (oostatic factor) has been purified from the ovaries of femaleAedes aegypti.The factor is a decapeptide with a molecular mass of 1047.6. The primary sequence has been determined as NH2‐Tyr‐Asp‐Pro‐Ala‐Pro‐Pro‐Pro‐Pro‐Pro‐Pro‐COOH from mass spectra recorded on a quadrupole Fourier transform instrument. The amino acid sequence exhibits sequence correlation to mammalian, plant, and several viral proteins. Injection of synthetic analogs into mosquitoes, biting midges, flies, and fleas inhibited proteolytic enzyme biosynthesis in the midgut. Binding studies with [3H]oostatic factor indicated that the midgut epithelial cells have a factor‐specific receptor.— Borovsky, D.; Carlson, D. A.; Griffin, P. R.; Shabanowitz, J.; Hunt, D. F. Mosquito oostatic factor: a novel decapeptide modulating trypsin‐like enzyme biosynthesis in the midgut.FASEB J.4: 3015‐3020; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.12.2394318

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

Cellular DNA fragmentation can be induced in many biological instances without plasma membrane damage. The fungal metabolite, cytochalasin B, is capable of modifying numerous cellular functions related to DNA synthesis. In this work it is demonstrated that cytochalasin B is capable of inducing DNA fragmentation in a number of cells lines. This DNA fragmentation occurs before plasma membrane lysis and over a period of hours. Cytochalasin E and villin, agents that act on the microfilaments, also induce DNA fragmentation. Phorbol dibutyrate, a diacylglyceral analog, is able to inhibit cytochalasin B‐induced DNA fragmentation in a dose‐dependent fashion. These findings support the interpretation that cytochalasin B is inducing DNA fragmentation via its effect on the actin filaments.— Kolber, M. A., Broschat, K. O., Landa‐Gonzalez, B. Cytochalasin B induces cellular DNA fragmentation.FASEB J.4: 3021‐3027; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.12.2394319

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

Candida tropicalisperoxisomes contain a 905‐residue trifunctional enzyme with hydratase‐dehydrogenase‐epimerase activity that is important in fatty acid β‐oxidation. At its amino terminus are two tandem copies of an ~280 residue domain of unknown function. We provide evidence that this domain is homologous to oxidoreductases used for metabolizing sugars and synthesizing antibiotics and steroids such as estradiol, androstenedione, corticosterone, and hydrocortisone. The trifunctional enzyme shows no sequence similarity to the bifunctional hydratase‐dehydrogenase found in animal peroxisomes and plant glyoxysomes, which are homologs of each other. We suggest that theC. tropicalistrifunctional enzyme and the animal and plant bifunctional enzymes have different ancestors.— Baker, M. E. A common ancestor forCandida tropicalisand dehydrogenases that synthesize antibiotics and steroids.FASEB J.4: 3028‐3032; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.12.2394320

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

An experimental kidney infarction model was developed in the mouse to study the uptake of a radiolabeled monoclonal antibody previously shown to bind to degenerating cells in malignant tumors. To determine if this approach is applicable to normal tissue and cell degeneration, kidney infarction was produced by clamping the mouse renal artery for 3 h using surgical procedures. Various groups of mice were injected with131I‐labeled TNT‐1 F(ab‘)2monoclonal antibody directed against nuclear histone antigens at varying intervals after surgery. Imaging, biodistribution, autoradiography, and histological studies were performed on each group of mice, including sham‐operated controls, to quantitate the level of binding and localize the uptake of label in clamped and unclamped (contralateral) kidneys. As additional controls, clamped mice were administered radiolabeled irrelevant monoclonal antibody Lym‐1 or mouse albumin. The results showed a marked selective uptake of radiolabeled TNT‐1 F(ab‘)2in the injured clamped kidney compared with the untreated kidney and other normal organs of the mouse. These studies define a model of normal organ necrosis that may be useful for study of the kinetics of antibody uptake in infarcted tissues.— Chen, F.‐M.; Wisner, J. R., Jr.; Omachi, H.; Renner, I. G.; Taylor, C. R.; Epstein, A. L. Localization of monoclonal antibody TNT‐1 in experimental kidney infarction of the mouse.FASEB J.4: 3033‐3039; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.12.2394321

出版商:Wiley    

年代:1990

数据来源: WILEY