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PubMedDate not supplied

[Effect of the content of crude plant protein in the ration on the utilization of urea in dairy cattle. 2. 15N-urea metabolism].

The metabolism of 15N-urea in the rations of dairy cows was investigated in dependence on the crude protein content of the rations. With energy concentration remaining unchanged, the rations contained 10.7 (I), 13.7 (II) and 17.1 (III)% plant crude protein and, after the supplementation of 150 g urea per animal and day, a total of 13.8, 16.7 and 20.2% crude protein in the dry matter. The urea was intraruminally infused during the feeding in the morning and the evening. In the morning feeding of each 1st measuring day it was labelled with 27.5 atom-% 15N-excess (15N'). The degree of labelling with 15N' of the N-fraction of rumen fluid, contents of the duodenum, faeces and milk, precipitable with trichloric acetic acid (TCA) decreased with the rising protein level of the ration. This effect was bigger than could be expected considering the low 15N'-quota in the total-N of the ration. In the sequence I ... III, 52.7, 32.2 and 30.6% of the 15N'-amount taken in passed the duodenal re-entrant cannula in TCA-precipitable form within 72 hours after the 15N-application. 33.3, 21.9 and 22.6% were apparently absorbed in the intestines as TCA-precipitable N within 120 h after the 15N'-application. In the same period 31.7, 43.1 and 72.8% of the 15N' taken in were excreted in urine. 12.3, 9.6 and 5.8% of the applied 15N' were found in milk protein. One can conclude that the utilisation of urea-N decreases with the rising level of crude protein in the ration and that, however, urea-N is still biochemically utilised when there is an excess of plant-N in the ration.

Animals↗
PubMed2004

The eight-cysteine motif, a versatile structure in plant proteins.

A number of protein sequences deduced from the molecular analysis of plant cDNA or genomic libraries can be grouped in relation to a defined number of cysteine residues located in distinct positions of their sequences. This is the case for a group of around 500 polypeptides from different species that contain a small domain (less than 100 amino acids residues) displaying a pattern of eight-cysteines in a specific order. The plant sequences containing this motif belong to proteins having different functions, ranging from storage, protection, enzyme inhibition and lipid transfer, to cell wall structure. The eight-cysteine motif (8CM) appears to be a structural scaffold of conserved helical regions connected by variable loops, as observed by three-dimensional structure analysis. It is proposed that the cysteine residues would form a network of disulfide bridges necessary, for the maintenance of the tertiary structure of the molecule together with the central helical core, while the variable loops would provide the sequences required for the specific functions of the proteins.

Amino Acid Motifs↗
PubMed1996

A rolB regulatory factor belongs to a new class of single zinc finger plant proteins.

A protein which binds to the regulatory domain B necessary for expression of the plant oncogene rolB in (root) meristems contains a single zinc finger of a novel type conserved in dicots and monocots. Band shift analysis revealed the presence in tobacco nuclei of a protein selectively binding to domain B, a tetramer of which was used to isolate a cDNA (NtBBF1, Nicotiana tabacum rolB domain B Factor 1) from a tobacco expression library. The corresponding genomic clone was also isolated. The protein encoded by NtBBF1 contains a single C2C2 zinc finger, and its target sequence in domain B was identified by means of mutagenized oligonucleotides. The DNA-binding capability of the zinc finger was assessed by means of a fusion of this latter with the glutathione-S-transferase protein, that was shown to bind the same target sequence as NtBBF1. A number of other tobacco cDNAs encoding different proteins with a domain (BBF domain) encompassing the zinc finger identical to NtBBF1 were also isolated. Furthermore, a cDNA encoding a protein with an almost identical single zinc finger was isolated from Arabidopsis. A very closely related zinc finger has very recently been identified in maize transcription factors and termed the Dof domain. It is proposed that the tobacco, Arabidopsis and maize BBF/Dof domain proteins are members of a new broad family of plant transcription factors acting through a single zinc finger widely utilized in the plant kingdom.

Amino Acid Sequence↗
PubMed2004

Activation of Arp2/3 complex-dependent actin polymerization by plant proteins distantly related to Scar/WAVE.

The Arp2/3 complex, a highly conserved nucleator of F-actin polymerization, plays a key role in the regulation of actin dynamics eukaryotic cells. In animal cells and yeasts, Wiskott-Aldrich Syndrome protein (WASP)/suppressor of cAMP receptor (Scar)/WASP family verprolin homologous (WAVE) family proteins activate the Arp2/3 complex in response to localized cues. Like other eukaryotes, plants have an Arp2/3 complex, which has recently been shown to play an important role in F-actin organization and cell morphogenesis. However, no activators of the Arp2/3 complex have been identified in plants, which lack obvious homologs of WASP/Scar/WAVE family proteins. Here, we identify a family of Scar/WAVE-related plant Arp2/3 activators. Like Scar/WAVE proteins, four proteins identified in Arabidopsis thaliana (AtSCAR1 to AtSCAR4) and one in maize (ZmSCAR1) have a C-terminal WASP homology 2 (WH2)/acidic (WA)-verprolin homology/cofilin homology/acidic (VCA)-like domain, which we show can activate the bovine Arp2/3 complex. At their N termini, AtSCAR1 to ATSCAR4, along with a fifth protein lacking a VCA/WA-like domain at its C terminus (At4g18600), are related to the N-terminal Scar homology domains of Scar/WAVE family proteins. Analysis of gene expression patterns suggests functional redundancy among members of the AtSCAR family. Full-length AtSCAR1 and ATSCAR3 proteins and their Scar homology domains bind in vitro to AtBRICK 1 (AtBRK1), the Arabidopsis homolog of HSPC300, a WAVE-binding protein recently identified as a component of a complex implicated in the regulation of Scar/WAVE activity. Thus, AtSCAR proteins are likely to function in association with AtBRK1, and perhaps other Arabidopsis homologs of WAVE complex components, to regulate activation of the Arp2,3 complex in vivo.

Actin-Related Protein 2↗
PubMed1997

Primary structures of two ribonucleases from ginseng calluses. New members of the PR-10 family of intracellular pathogenesis-related plant proteins.

The amino acid sequences of two ribonucleases from a callus cell culture of Panax ginseng were determined. The two sequences differ at 26% of the amino acid positions. Homology was found with a large family of intracellular pathogenesis-related proteins, food allergens and tree pollen allergens from both dicotyledonous and monocotyledonous plant species. There is about 30% sequence difference with proteins from species belonging to the same plant order (Apiales: parsley and celery), 60% with those from four other dicotyledonous plant orders and about 70% from that of the monocotyledonous asparagus. More thorough evolutionary analyses of sequences lead to the conclusion that the general biological function of members of this protein family may be closely related to the ability to cleave intracellular RNA and that they have an important role in cell metabolism. As the three-dimensional structure of one of the members of this protein family has been determined recently [Gajhede et al., Nature Struct Biol 3 (1996) 1040-1045], it may be possible to assign active-site residues in the enzyme molecule and make hypotheses about its mode of action. Structural features in addition to the cellular site of biosynthesis indicate that this family of ribonucleases is very different from previously investigated ones.

Allergens↗
PubMed2002

Animal versus plant protein meals in individuals with type 2 diabetes and microalbuminuria: effects on renal, glycemic, and lipid parameters.

OBJECTIVE: To determine, for individuals with type 2 diabetes and microalbuminuria, the effects of 6 weeks of meals containing plant-based protein (PP) versus meals with predominantly animal-based protein (AP) on renal function and secondarily on glycemia, lipid levels, and blood pressure. RESEARCH DESIGN AND METHODS: In a randomized crossover trial, we compared 6 weeks of meals containing only PP with meals containing primarily AP (60% animal, 40% plant) in 17 subjects with type 2 diabetes and microalbuminuria treated with diet and/or oral antidiabetic agents. Protein content was equivalent to the average American diet, and calories provided weight maintenance. Nutrients were equivalent between the two diets. Meals were prepared and packaged by a metabolic kitchen staff and were sent home weekly. At the beginning and end of each 6-week period, subjects were studied for 36 h on a metabolic unit. RESULTS: There were no significant differences between diets for glomerular filtration rate, renal plasma flow, albumin excretion rate, total cholesterol, HDL cholesterol, triglyceride area under the curve (AUC), glucose and insulin AUC, HbA(1c,) blood pressure, or serum amino acids. For both diets, at the end of the treatment periods as compared with baseline, total cholesterol was significantly lower (PP and AP: from 4.75 to 4.34 mmol/l, P < 0.01), HbA(1c) had significantly improved (PP: from 8.1 to 7.5%, P < 0.01; AP: from 7.9 to 7.4%, P < 0.01), and diastolic blood pressure was significantly lower (PP: from 83 to 80 mmHg, P < 0.02; AP: from 82 to 78, P < 0.02). CONCLUSIONS: There is no clear advantage for the recommendation of diets containing only PP rather than diets containing protein that is primarily animal-based for individuals with type 2 diabetes and microalbuminuria. There are, however, potential lipid, glycemic, and blood pressure benefits for following a carefully constructed, weight-maintaining, healthy diet, regardless of protein source.

Adult↗
PubMed2001

Nuclear localization of the plant protein Ser/Thr phosphatase PP7.

Recently we identified novel plant Ser/Thr phosphatases, termed PP7, which belong to the PPP family and have no known close homologs in other kingdoms. We now addressed the intracellular location of Arabidopsis thaliana PP7 using GFP fusions and confocal laser scanning microscopy. PP7. GFP fusion was expressed transiently or stably in Nicotiana benthamiana. PP7. GFP was found to be a predominantly nuclear protein. Effects of cytoskeleton-disrupting drugs indicate that cytoskeleton may be required for efficient PP7. GFP delivery to the nucleus. Deletion of a potential nuclear localization signal in the first insert in the catalytic domain, as well as exposure to the dark, cold, high salinity and abscisic acid failed to prevent nuclear localization of PP7. GFP. Deletion of the 44 C-terminal amino acids resulted in a fusion protein located exclusively in the cytoplasm. The results suggest a possible similarity of the nuclear targeting signals in PP7 and the PP5/PPT subfamily.

Abscisic Acid↗
PubMed2000

Differences in zero-force and force-driven kinetics of ligand dissociation from beta-galactoside-specific proteins (plant and animal lectins, immunoglobulin G) monitored by plasmon resonance and dynamic single molecule force microscopy.

Protein-carbohydrate interactions are involved in diverse regulatory processes. To help understand the mechanics and kinetics of dissociation of receptor-ligand complexes, we have analyzed the separation of lactose and the N-glycan chains of asialofetuin (ASF) from three lectins and an immunoglobulin G fraction by surface plasmon resonance at zero force and by atomic force microscopy with variations of the external force. While the (AB)2 agglutinins from Ricinus communis (RCA) and Viscum album (VAA) show structural homology, the homodimeric galectin-1 from bovine heart (BHL) has no similarity to the two plant lectins except for sharing this monosaccharide specificity. The beta-galactoside-binding immunoglobulin G (IgG) fraction from human serum provides a further model system with distinct binding-site architecture. The k(off) constants for the two plant agglutinins were independent of the nature of the ligand at 1.1-1.3 x 10(-3) s(-1), whereas the geometry of ligand and binding site presentation affected this parameter for BHL (0.5 x 10(-3) s(-1) for lactose and 1 x 10(-3) s(-1) for ASF) and IgG (1.3 x 10(-3) s(-1) for lactose and 0.55 x 10(-3) s(-1) for ASF). When assessing comparatively the rupture forces at a loading rate of 3 nN/s with lactose as ligand, 34 +/- 6 pN (BHL), 36 +/- 4 pN (IgG), 47 +/- 7 pN (VAA), and 58 +/- 9 pN (RCA) were measured. For the same loading rate the rupture forces for the receptor-ASF interactions were found to be 37 +/- 3 pN (BHL), 43 +/- 5 pN (VAA), 45 +/- 6 pN (IgG), and 65 +/- 9 pN (RCA). The variation of the pulling velocity revealed in all cases a linear dependence between the rupture force and the natural logarithm of the loading rate. Performing probability density and Monte Carlo calculations, the potential barrier widths, which determine the inverse dynamic dependence with the rate of force elevation, increased from 4 A (RCA) and 7 A (VAA and IgG) to 10 A (BHL) for the receptor-lactose interactions. Presenting ASF as ligand potential widths of 4 A for RCA and IgG and 6 A for VAA and BHL were obtained. Since the dissociation kinetics at zero force apparently cannot predict the behavior in force-driven experiments, these results reveal new insights into biological functions. The dissociation kinetics under force helps to explain the difference in the toxic potency of VAA and RCA and points to a function of the galectin in cis-crosslinking and in transient trans-bridging.

Animals↗
PubMed1985

Studies on the development of infant foods from plant protein sources. Part II. Effect of processing conditions on the chemical and nutritive properties of chickpea (Cicer arietinum).

In order to improve the taste, flavor and nutritional quality of chickpea (Cicer arietinum), various processing conditions were studied. The decorticated samples were processed under various conditions, either by presoaking or non-soaking in water or sodium carbonate solution. The proteins were also isolated from water or carbonate-presoaked chickpea and subjected to various processing. Carbonate-presoaked samples gave slightly lower protein and ash values. No major changes in other constituents were observed. Subjective analysis of the intensity of characteristic chickpea flavor in processed samples was carried out, indicating some improvement in the carbonate-presoaked samples. Carbonate-treated samples exhibited a lighter color. The carbonate presoaking procedure had no adverse effect on the availability of lysine and nitrogen solubility index (NSI), as compared to the water-presoaking procedure. The time required to inactivate trypsin inhibitors in carbonate-presoaked chickpea at boiling temperature, was half that required in the case of water-presoaked ones. Under the conditions used in treating chickpea with sodium carbonate, no beneficial effect was observed in reducing the tannin content. No significant differences were observed in net protein ratio (NPR) among the various processed chickpea samples, even though in some cases isolated protein gave significantly lower NPR values. Digestibility values were higher for isolated protein than for whole chickpea samples.

Animals↗
PubMed2007

Recognition of a PP2C interaction motif in several plant protein kinases.

Protein phosphatase 2Cs (PP2Cs) constitute a major class of phosphatases in plants. PP2Cs play important roles in many signaling pathways by countering the action of specific protein kinases. In addition to their role in several environmental stress-related signal transduction pathways, they are also involved in plant metabolism. Protein phosphatases often physically associate with their protein kinase counterparts. One approach to understanding PP2C function is to identify their interacting protein kinases. We describe a yeast two-hybrid assay system used in our lab to determine the interaction between members of the PP2C family and protein kinases in the SOS2 family. This chapter and the cited articles describing related work might be of help in discovering interactions between other protein phosphatases and kinases.

Binding Sites↗