Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The expression of some nuclear genes in Saccharomyces cerevisiae, such as the CIT2 gene, which encodes a glyoxylate cycle isoform of citrate synthase, is responsive to the functional state of mitochondria. Previous studies identified a basic helix-loop-helix-leucine zipper (bHLH/Zip) transcription factor encoded by the RTG1 gene that is required for both basal expression of the CIT2 gene and its increased expression in respiratory-deficient cells. Here, we describe the cloning and characterization of RTG3, a gene encoding a 54-kDa bHLH/Zip protein that is also required for CIT2 expression. Rtg3p binds together with Rtg1p to two identical sites oriented as inverted repeats 28 bp apart in a regulatory upstream activation sequence element (UASr) in the CIT2 promoter. The core binding site for the Rtg1p-Rtg3p heterodimer is 5'-GGTCAC-3', which differs from the canonical E-box site, CANNTG, to which most other bHLH proteins bind. We demonstrate that both of the Rtg1p-Rtg3p binding sites in the UAS(r) element are required in vivo and act synergistically for CIT2 expression. The basic region of Rtg3p conforms well to the basic region of most bHLH proteins, whereas the basic region of Rtg1p does not. These findings suggest that the Rtg1p-Rtg3p complex interacts in a novel way with its DNA target sites.
Mol Cell Biol 1997 Mar
PMID:A basic helix-loop-helix-leucine zipper transcription complex in yeast functions in a signaling pathway from mitochondria to the nucleus. 903 38

The amino-terminal oxygen-binding unit Rta of the Rapana thomasiana hemocyanin is a glycoprotein with a carbohydrate content of 4.8% (w/w). Sugar analysis revealed as monosaccharide constituents xylose, fucose, 3-O-methylgalactose, mannose, galactose, N-acetylgalactosamine and N-acetylglucosamine residues. On subtracting the carbohydrate contribution from the molecular mass of 49,698 Da, determined by laser desorption mass spectrometry for Rta, an M(r) value of 47,318 Da was determined for the polypeptide part of the functional unit. The Rapana hemocyanin oxygen-binding unit Rta contains 400 residues in a single polypeptide chain. The nearly complete amino acid sequence (about 90%) is determined. This is the first report on a sequence of a marine gastropod oxygen-binding unit and also on a molluscan hemocyanin amino-terminal unit. Comparison of the Rta sequence with those of other molluscan hemocyanin units, localized in the C-terminus or in the middle of the respective multidomain polypeptide chains, revealed 42-46% homology (52-55%, including isofunctional residues). Probably, all molluscan oxygen-binding units evolved from a common ancestral gene.
Comp Biochem Physiol B Biochem Mol Biol 1997 May
PMID:Amino-terminal oxygen-binding functional unit of the Rapana thomasiana grosse (gastropod) hemocyanin: carbohydrate content, monosaccharide composition and amino acid sequence studies. 918 18

Type I collagen is the most prevalent member of the fibril forming family of collagens in higher vertebrates and its heterotrimeric form is comprised of two alpha 1(I) chains and one alpha2(I) polypeptide chain. The functional importance of having two distinct chain types in type I collagen is largely undefined. The existence of a mouse model with a Cola-2 gene mutation (termed oim) that results in non-functional pro alpha 2(I) chains presents a unique opportunity to explore changes in collagen structure resulting from the complete (oim/oim mice) and partial (oim/+ mice) loss of functional alpha 2(I) chains. Tail tendon is a tissue with a well-defined, hierarchical organization of type I collagen. X-ray diffraction studies on oim/oim versus control tendons indicate that the total absence of alpha 2(I) chains results in a decrease in the order of axial packing and a loss of crystalline lateral packing. This suggests that the non-equivalence of three chains is an important determinant of lateral interactions between adjacent molecules and may be involved in the long-range axial order in type I collagen-containing tissues. Both homotrimeric and heterotrimeric type I collagen molecules are found in heterozygous oim mice and these appear to be present in the same co-polymeric fibrils, preventing crystalline lateral packing. In addition to these changes at a fibrillar level, the absence of the alpha 2(I) chain results in an increased enzymatic susceptibility at one site. The oim/oim mice are observed to have reduced body size and smaller tendon bundles, which may be a consequence of these molecular and fibrillar changes in collagen. Furthermore, it is likely that a similar alteration in the molecular packing of collagen in bone fibrils contributes to the osteopenia and decreased bone strength in mice with the oim mutation that are also characteristic of human osteogenesis imperfecta.
J Mol Biol 1997 Jul 11
PMID:Altered collagen structure in mouse tail tendon lacking the alpha 2(I) chain. 923 28

Sugar-lectin binding assay was developed as a simple method which employed direct coating of microtiter plate with galactose-binding lectins. Biotin-galactose conjugate was used to bind to the immobilized lectins. The bound conjugate was then detected using streptavidin-horseradish peroxidase. Using the assay in conjunction with various competing carbohydrates, jackfruit lectin from Artocarpus heterophyllus was found to be specific for alpha-anomer of galactoside with an aromatic residue.
Biochem Mol Biol Int 1997 Jun
PMID:Determination of sugar specificity of jackfruit lectin by a simple sugar-lectin binding assay using microtiter plate. 923 39

Glycosidic residues of the mammalian zona pellucida (ZP) are known to be involved in sperm binding, suggesting the presence of complementary carbohydrate binding sites on spermatozoa. However, in previous studies, in which sperm suspensions were incubated with monosaccharides, no inhibitory effect was observed. Results of studies in which sperm were treated shortly after swim-up suggest that the use of non-capacitated cells may explain the apparently conflicting results. In the present report, we studied the effect of preincubation of capacitated spermatozoa with different monosaccharides on their ability to bind to ZP. After 5 h under capacitating conditions, spermatozoa were incubated in medium with or without a monosaccharide, resuspended in fresh medium and used for hemizona (HZ) binding assay. When ZH were incubated with spermatozoa treated with N-acetyl-D-glucosamine, D-mannose, D-fucose, L-fucose or D-galactose, a significant decrease in the number of spermatozoa bound was observed (level of inhibition: 62, 58, 82, 68 and 48% respectively) while treatment of spermatozoa with D-glucose produced no inhibition. Sugar treatment neither altered sperm motility nor the rate of acrosome reaction. These results suggest that N-acetylglucosamine, mannose, fucose and galactose residues are involved in human sperm-zona pellucida binding in vitro.
Mol Hum Reprod 1997 May
PMID:Glycosidic residues involved in human sperm-zona pellucida binding in vitro. 923 24

Homeodomain-leucine zipper (HD-Zip) proteins are putative transcription factors identified only in plants. The study of the DNA-binding properties of the ATHB-1 and -2 HD-Zip (HD-Zip-1 and -2) domains showed that they interact with DNA as homodimers and recognize two distinct 9 bp pseudopalindromic sequences, CAAT(A/T)ATTG (BS-1) and CAAT(G/C)ATTG (BS-2), respectively, as determined by selecting high-affinity binding sites from random-sequence DNA. Here, we report a mutational analysis of the HD-Zip-2 domain. We determined that conserved amino acid residues of helix 3, Val47 and Asn51, and Arg55 are essential for the DNA-binding activity of the HD-Zip-2 domain. We demonstrated that the preferential recognition of a G/C base-pair at the central position by the HD-Zip-2 domain is abolished either by the replacement of Arg55 with lysine or by the substitution of Glu46 and Thr56 with the corresponding residues of the HD-Zip-1 domain (alanine and tryptophan, respectively). In contrast, substitution of Arg55 with lysine in the HD-Zip-1 domain significantly reduced DNA-binding activity without changing the specificity of recognition. Finally, we determined that differences in residues outside helix 3 further contribute to the DNA-binding specificity of the HD-Zip domain. Taken together, the data strongly suggest that the preferential recognition of BS-2 and -1 by the HD-Zip-2 and -1 domains, respectively, may be attributable to a distinct orientation of the side-chain of Arg55 in these two domains.
J Mol Biol 1997 Dec 05
PMID:DNA-binding specificity of the homeodomain-leucine zipper domain. 940 40

To investigate early events of Agrobacterium-mediated transformation of apple cultivars, a synthetic green fluorescent protein gene (SGFP) was used as a highly sensitive, vital reporter gene. Leaf explants from four apple cultivars ('Delicious', 'Golden Delicious', 'Royal Gala' and 'Greensleeves') were infected with Agrobacterium EHA101 harboring plasmid pDM96.0501. Fluorescence microscopy indicated that SGFP expression was first detected 48 h after infection and quantitative analysis revealed a high T-DNA transfer rate. Plant cells with stably incorporated T-DNA exhibited cell division and developed transgenic calli, followed by formation of transgenic shoots at low frequencies. The detection of SGFP expression with an epifluorescence stereomicroscope confirmed the effectiveness of SGFP as a reporter gene for detection of very early transformation events and for screening of putative transformants. The efficiency of the transformation and regeneration process decreased ca. 10,000-fold from Agrobacterium infection to transgenic shoot regeneration, suggesting that factors other than Agrobacterium interaction and T-DNA transfer are rate-limiting steps in Agrobacterium-mediated transformation of apple.
Plant Mol Biol 1998 Jun
PMID:Investigation of Agrobacterium-mediated transformation of apple using green fluorescent protein: high transient expression and low stable transformation suggest that factors other than T-DNA transfer are rate-limiting. 961 21

Structural studies were performed in two atypical polysaccharides, PS-1 and PS-2 isolated from the broth of a Tn5 mutant strain of Xanthomonas campestris. Sugar composition, methylation and nuclear magnetic resonance analyses were determined. PS-1 is composed by repeating trisaccharide units containing D-glucose, D-mannose and having the structure. carbohydrate sequence [see text]. Preliminary studies on the PS-2 show a polymer composed in a large extent of rhamnose. Unexpectedly, this polysaccharide is soluble in alcoholic solutions.
Cell Mol Biol (Noisy-le-grand) 1998 May
PMID:Structure of an extracellular mannosylated cellulose produced by a mutant strain of Xanthomonas campestris. 962 Apr 40

The glucose transporter of human erythrocytes (Glut1) was reconstituted into soybean phospholipid liposomes by a method of direct incorporation using the nonionic detergent n-octyl beta-D-glucopyranoside. The reconstituted proteoliposomes were proved to be intact and low ionic permeability. Freeze-fracture electron microscopy study showed that the diameter of the proteoliposomes was about 150 +/- 50 nm and the protein was randomly distributed. The kinetic parameters of the reconstituted transporter were: Km =16.23 mmol/L, Vmax = 34.48 nmol/sec x mg protein. Furthermore, about 90% of the glucose transporter in the reconstituted proteoliposomes were orientated inside-out. Until now it is a more efficient method for uni-directional reconstitution of Glut1 with good reproducibility and higher transport activity.
Biochem Mol Biol Int 1998 May
PMID:A method for uni-directional reconstitution of human erythrocyte glucose transporter. 962 77

The dioxin receptor is a ligand-regulated transcription factor that mediates signal transduction by dioxin and related environmental pollutants. The receptor belongs to the basic helix-loop-helix (bHLH)-Per-Arnt-Sim (PAS) family of factors, which, in addition to the bHLH motif, contain a PAS region of homology. Upon activation, the dioxin receptor dimerizes with the bHLH-PAS factor Arnt, enabling the receptor to recognize xenobiotic response elements in the vicinity of target genes. We have studied the role of the PAS domain in dimerization and DNA binding specificity of the dioxin receptor and Arnt by monitoring the abilities of the individual bHLH domains and different bHLH-PAS fragments to dimerize and bind DNA in vitro and recognize target genes in vivo. The minimal bHLH domain of the dioxin receptor formed homodimeric complexes, heterodimerized with full-length Arnt, and together with Arnt was sufficient for recognition of target DNA in vitro and in vivo. In a similar fashion, only the bHLH domain of Arnt was necessary for DNA binding specificity in the presence of the dioxin receptor bHLH domain. Moreover, the bHLH domain of the dioxin receptor displayed a broad dimerization potential, as manifested by complex formation with, e.g. , the unrelated bHLH-Zip transcription factor USF. In contrast, a construct spanning the dioxin receptor bHLH domain and an N-terminal portion of the PAS domain failed to form homodimers and was capable of dimerizing only with Arnt. Thus, the PAS domain is essential to confer dimerization specificity of the dioxin receptor.
Mol Cell Biol 1998 Jul
PMID:Role of the PAS domain in regulation of dimerization and DNA binding specificity of the dioxin receptor. 963 92


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>