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 DNA-binding C-terminal domains of the regulatory proteins Fnr from Escherichia coli and FixK from Rhizobium meliloti have been modelled on the basis of their homologies to the CAP protein from E. coli. Residues Glu181, Thr182 and Arg185 of CAP, which are exposed residues of the DNA-recognition helix alpha F, are conserved in Fnr and FixK. However, Arg180 and Gly184 are substituted by Val and Ser respectively in Fnr. We propose that this valine makes a Van der Waals' contact with the first thymine in the Fnr consensus TTGA-N6-TCAA, and that the serine contributes to the binding by displacing a thymine-bound water molecule. The corresponding residues in FixK, Ile and Ser allow the same interactions with a thymine. Therefore we predict that FixK may recognize the same sites as Fnr. This is supported experimentally by showing that Fnr can substitute for FixK in activating the fixN gene in E. coli.
J Mol Recognit 1989 Nov
PMID:Model-building of Fnr and FixK DNA-binding domains suggests a basis for specific DNA recognition. 256 29

In this report we describe the expression of the ras proto-oncogene p21 protein in various tissues during normal fetal development. Conventional, formalin fixed and paraffin-embedded sections of normal organs were examined from fetuses ranging 9 to 42 weeks of gestation. Immunohistochemical localization of ras p21 was accomplished using the broadly reactive, mouse monoclonal antibodies RAP-5 and Y13-259. The monoclonal antibody DWP, which is specific for a mutated form of ras p21 having a valine/cysteine at amino acid position 12, was also used. Detectable expression of the p21 protein was seen at different time periods during fetal development depending on the tissue. The expression of ras p21 (as detected by RAP-5 and Y13-259) was noted in a wide range of cell types and tissues; intense immunostaining was noted in epithelial cells of the gastrointestinal tract, exocrine and endocrine pancreas, renal tubules and transitional urotheliem, as well as in other tissues. This immunostaining generally, but not invariably, corresponded with patterns previously reported in benign and/or malignant neoplasms of adult tissues. In most instances ras p21 expression, when present, occurred during periods of rapid growth in given organ systems. However, some actively proliferating fetal tissues such as thymus and spleen, failed to express detectable ras p21 suggesting that factors other than cell cycle may influence its expression. No reactivity with DWP was noted in any of the tissues, suggesting that the mutated forms detected by this monoclonal antibody are not expressed during normal human embryogenesis. These data show that there is regulated expression, and broad distribution of this gene product in normal developing human fetal tissue.
Virchows Arch B Cell Pathol Incl Mol Pathol 1989
PMID:Expression of ras oncogene p21 during human fetal development as determined by monoclonal antibodies RAP-5, Y13-259, and DWP. 256 31

In this study we examined 214 cases of primary human pulmonary neoplasms for the expression of a mutated form of the ras oncogene p21 product, recognized by the monoclonal antibody (MCA) DWP. Adjacent serial sections from these same cases had previously been used to demonstrate the frequency of ras p21 expression using the broadly reactive anti-ras p21 MCA RAP-5. Confirmation of the increased expression of p21 was accomplished using MCA Y13-259. The use of adjacent tissue sections from these cases allows the direct comparison of the expression of the mutated and non-mutated forms of ras p21. If reactivity with DWP would prove to be significantly more restrictive than that of the "pan" ras MCAs, RAP-5 and Y13-259, it would lend support to the possibility that DWP (and similar MCAs which detect other specific mutations) could be used to define subsets of these neoplasms based on their specific ras p21 phenotype. Since one would anticipate that the valine/cysteine substitution at position 12 of the ras p21 would occur at only low frequencies in human tumors, our results with DWP are consistent with this hypothesis. As previously reported, RAP-5 reacted with a high proportion of lung tumors (100/214 or 47%). In this report, we demonstrate the selective expression of the mutation recognized by the MCA DWP in only 5% of these same tumors (13/214), and that the expression of this mutated form is not restricted to any of the conventional histological subclasses of pulmonary neoplasms.
Virchows Arch B Cell Pathol Incl Mol Pathol 1989
PMID:Immunohistochemical analysis of normal and mutated ras oncogene p21 expression in human pulmonary and pleural neoplasms. 256 85

We have evaluated the participation of the lysosomal degradation pathway in the increased protein degradation induced by nutrient deprivation in transformed cells. To this end we used a clone, 12-1a, derived from a murine teratocarcinoma cell line (F9 12-1) induced to differentiate by culture in retinoic acid. Culture of 12-1a cells, prelabeled with L-[U-14C]valine, in nutrient-deprived medium (Hanks' balanced salt solution plus Ca++) stimulated the protein degradation rate from 0.9% hr to 1.4% hr. Morphometric analysis demonstrated that during nutrient deprivation, the volume density of lysosomes increased 3-fold; the numerical density of lysosomes increased 2-fold; the mean area of lysosomal profiles increased 1.7-fold (1.40 microns2 vs 0.81 microns2). The volume density and numerical density of the dense bodies tended to decrease by approximately 60% without any change in the mean volume of the dense bodies. These data indicate that nutrient deprivation increases protein degradation in transformed cells by increasing the sequestration of cytoplasm into the lysosomes. The decrease in the number of dense bodies indicates that these structures (also termed residual bodies) are functional in transformed cells and merge with the lysosomes to provide more degradative enzymes to enhance proteolysis. This study provides direct evidence that serum factors and nutrients play a crucial role in modulation of lysosomal protein degradation in transformed cells.
Exp Mol Pathol 1989 Feb
PMID:Stimulation of autophagic protein degradation by nutrient deprivation in a differentiated murine teratocarcinoma (F9 12-1a) cell line. 264 43

The ilvIH operon of Escherichia coli encodes acetohydroxyacid synthase III, an isoenzyme involved in branched-chain amino acid biosynthesis. Transcription of the ilvIH operon is repressed by growing cells in the presence of leucine (C.H. Squires, M. DeFelice, S.R. Wessler, and J.M. Calvo, J. Bacteriol. 147:797-804, 1981). A protein in crude extracts of E. coli, termed the ilvIH-binding (IHB) protein, bound specifically in vitro to DNA upstream of the ilvIH operon. The binding protein, partially purified by Polymin precipitation, gel filtration, and phosphocellulose chromatography, has a native molecular weight of 43,000 and is composed of two subunits of identical size. As determined by protection against lambda exonuclease and DNase I, the protein binds within a region -190 to -260 relative to the start point of transcription. In addition, the IHB protein binds to a site between positions -100 and -40. The following evidence suggests that binding of this protein to the region upstream of ilvIH is related to the regulation of this operon by leucine. Binding of the IHB protein to the ilvIH regulatory region in vitro was reduced by leucine but not by isoleucine, valine, or threonine. In a mutant strain isolated by M.V. Ursini, P. Arcari, and M. DeFelice (Mol. Gen. Genet. 181:491-496, 1981), transcription was not repressed by leucine. A protein in extracts of this mutant strain bound to the ilvIH regulatory region, but the complex migrated through agarose gels with a mobility different from that of the complex formed by wild-type protein. Furthermore, a concentration of leucine that substantially reduced binding of the wild-type to DNA did not affect binding of the protein from the mutant strain. A simple model consistent with these findings is that transcription from the ilvIH promoter is stimulated by binding the IHB protein to one or more sites upstream of the promoter and that leucine interferes with this binding.
 ...
PMID:A protein that binds to the regulatory region of the Escherichia coli ilvIH operon. 264 91

gamma-Crystallins are a family of low molecular weight proteins found in high concentration in the densely packed regions of high refractive index in vertebrate lenses. Certain members have the characteristic property of a high critical temperature (tc) for phase separation. We report the three-dimensional structure determination of such a protein, bovine lens gamma IVa-crystallin, which has been refined to give an X-ray R-factor of 0.143. Its high tc contrasts with the low tc gamma II-crystallin, whose structure we have already published. The root mean square difference between the alpha-carbon atoms of these two proteins is 0.70 A and gamma IVa has an internal symmetry even higher than that of gamma II. The presence of a protein that exhibits the phenomenon of phase separation at body temperature renders the lens very susceptible to a transformation from transparent to an opaque state due to irregularities in the refractive index. Protein interactions of gamma IVa-crystallin have implications for the mechanism of cataract formation. Modes of self-association behaviour of gamma IVa-crystallin have been inferred from an analysis of the lattice interactions in the crystalline state, where the protein packing density is similar to that of the intact lens. It appears that the point mutation at position 103 from a serine residue in gamma II to a valine in gamma IVa gives rise to a lattice contact formed by two four-stranded beta-sheets in gamma IVa. A group-specific mutation at position 118 from leucine to phenylalanine induces subtle differences in core packing, leading to a reorganization around residue 103. However, the final phase separation determinant may be a complex combination of many side-chain functions.
J Mol Biol 1989 May 05
PMID:Packing interactions in the eye-lens. Structural analysis, internal symmetry and lattice interactions of bovine gamma IVa-crystallin. 273 25

We have fortuitously created an in-frame insertion mutation in the cloned ompR gene of Escherichia coli in the course of an experiment involving linker insertion mutagenesis. According to the DNA sequence, the mutant protein has an insertion at the 53rd amino acid residue, which replaced the original valine, with the sequence Ala-Leu-Glu. The expression level of the mutant protein, OmpRX6, in a minicell system, is similar to that of the wild-type protein and the size of the mutant is slightly larger than the wild type by approximately 300 daltons. This mutant was completely unable to activate porin expression as the wildtype does, and in addition, this phenotype was shown to be dominant over the wild type. Comparison of the amino acid sequence of OmpRX6 with those of a family of homologous bacterial regulatory proteins revealed that the mutation lies in a domain which is highly conserved among these proteins.
Mol Gen Genet 1988 Mar
PMID:A dominant mutation in Escherichia coli OmpR lies within a domain which is highly conserved in a large family of bacterial regulatory proteins. 283 39

Yeast strain 990 carries a mutation mapping to the oli1 locus of the mitochondrial genome, the gene encoding ATPase subunit 9. DNA sequence analysis indicated a substitution of valine for alanine at residue 22 of the protein. The strain failed to grow on nonfermentable carbon sources such as glycerol at low temperature (20 degrees C). At 28 degrees C the strain grew on nonfermentable carbon sources and was resistant to the antibiotic oligomycin. ATPase activity in mitochondria isolated from 990 was reduced relative to the wild-type strain from which it was derived, but the residual activity was oligomycin resistant. Subunit 9 (the DCCD-binding proteolipid) from the mutant strain exhibited reduced mobility in SDS-polyacrylamide gels relative to the wild-type proteolipid. Ten revertant strains of 990 were analyzed. All restored the ability to grow on glycerol at 20 degrees C. Mitotic segregation data showed that eight of the ten revertants were attributable to mitochondrial genetic events and two were caused by nuclear events since they appeared to be recessive nuclear suppressors. These nuclear mutations retained partial resistance to oligomycin and did not alter the electrophoretic behavior of subunit 9 or any other ATPase subunit. When mitochondrial DNA from each of the revertant strains was hybridized with an oligonucleotide probe covering the oli1 mutation, seven of the mitochondrial revertants were found to be true revertants and one a second mutation at the site of the original 990 mutation. The oli1 gene from this strain contained a substitution of glycine for valine at residue 22. The proteolipid isolated from this strain had increased electrophoretic mobility relative to the wild-type proteolipid.
Mol Gen Genet 1987 Apr
PMID:Nuclear and mitochondrial revertants of a mitochondrial mutant with a defect in the ATP synthetase complex. 288 22

During senescence in the filamentous fungus Podospora anserina, specific regions of the mitochondrial genome, termed senDNA are excised, ligated and amplified. We have cloned in their entirety three such autonomously replicating plasmids, alpha, beta and epsilon senDNA. None of these plasmids displayed cross-hybridization nor did we detect any significant DNA homology by computer analysis. The complete DNA sequence of the 2.5 kb alpha, the 5.5 kb epsilon and about 3.4 kb of the 9.8 kb beta senDNA is presented (kb = 10(3) base-pairs). These sequences were analyzed for the presence of consensus sequences common to introns, and it was found that alpha senDNA has the characteristics of a group II intron, epsilon senDNA contains three group I introns, and beta senDNA did not show relevant sequences in the 3.4 kb examined. Comparison of the 5' and 3'-flanking sequences of alpha senDNA with oxi 3 (Co I) amino acid sequences from Neurospora crassa and Saccharomyces cerevisiae revealed significant homology and provided strong support that the excised alpha senDNA itself consists entirely of an intron. Upstream from the oxi 3 gene a transfer RNA cysteine sequence was detected. beta senDNA contained four tRNA sequences, aspartic acid, serine, valine and tryptophan, and sequences homologous to URFC (untranslated reading frame C) as well as two new URFs. epsilon senDNA contained sequences homologous to ATPase 8 and URFl; URFl was interrupted by three group I introns. The excision site sequences, as located by S1 nuclease mapping were unique for each senDNA. Analysis for repeated units showed that each plasmid contained elements which could be involved in secondary structure required for the alignment of distal ends preparatory to excision. These results are interpreted in terms of the structural requirements of mobile elements including the possible involvement of reverse transcriptase in the excision-ligation-amplification process.
J Mol Biol 1985 Oct 20
PMID:Excision-amplification of mitochondrial DNA during senescence in Podospora anserina. DNA sequence analysis of three unique "plasmids". 299 55

The gene ompA encodes a major outer membrane protein of Escherichia coli. Localized mutagenesis of the part of the gene corresponding to the 21-residue signal sequence and the first 45 residues of the protein resulted in alterations which caused cell lysis when expressed. DNA sequence analyses revealed that in one mutant type the last CO2H-terminal residue of the signal sequence, alanine, was replaced by valine. The proteolytic removal of the signal peptide was much delayed and most of the unprocessed precursor protein was fractioned with the outer membrane. However, this precursor was completely soluble in sodium lauryl sarcosinate which does not solubilize the OmpA protein or fragments thereof present in the outer membrane. Synthesis of the mutant protein did not inhibit processing of the OmpA or OmpF proteins. In the other mutant type, multiple mutational alterations had occurred leading to four amino acid substitutions in the signal sequence and two affecting the first two residues of the mature protein. A reduced rate of processing could not be clearly demonstrated. Membrane fractionation suggested that small amounts of this precursor were associated with the plasma membrane but synthesis of this mutant protein also did not inhibit processing of the wild-type OmpA or OmpF proteins. Several lines of evidence left no doubt that the mature mutant protein is stably incorporated into the outer membrane. It is suggested that the presence, in the outer membrane, of the mutant precursor protein in the former case, or of the mutant protein in the latter case perturbs the membrane architecture enough to cause cell death.
Mol Gen Genet 1985
PMID:Lethal mutations in the structural gene of an outer membrane protein (OmpA) of Escherichia coli K12. 299 84


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