Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.4.25.1 (proteasome)
28,817 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The sequence of the amino-terminal 349 residues of rabbit muscle glycogen phosphorylase (EC 2.4.1.1) has been determined. Limited proteolysis of native phosphorylase b (841 residues, subunit molecular weight 97 412) by subtilisin BPN', Streptomyces alkaline protease, or elastase yielded two large segments (light and heavy). The light segment isolated from the subtilisin digest was cleaved at methionyl bonds with cyanogen bromide to yield eight major fragments and two minor overlapping fragments. The alignment of the major fragments was obtained by analysis of the two minor fragments, of five tryptic peptides containing methionine and of one large fragment generated by cleavage of an aspartylproline bond. Analysis of two cyanogen bromide fragments (CB14 and CB17) isolated from the intact molecule identified the sites susceptible to limited proteolysis and the overlap between the light and the heavy segments. Serine-14 and tyrosine-155 were identified as the residues involved in the covalent and allosteric controls of the enzyme, respectively. Residues 108 and 142 were identified as the cysteine residues reported to be involved in the aggregation of subunits.
...
PMID:Sequence of the amino-terminal 349 residues of rabbit muscle glycogen phosphorylase including the sites of covalent and allosteric control. 72 24

We have reported that proteasomes are expressed at abnormally high levels in various hematopoietic tumor cells (Kumatori, A., Tanaka, K., Inamura, N., Sone, S., Ogura, T., Matsumoto, T., Tachikawa, T., Shin, S., and Ichihara, A. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 7071-7075). In the present study, we examined changes in the expressions of proteasomes during growth of peripheral T-lymphocytes from healthy adults and differentiation of human leukemic cell lines. Up-regulation of mRNAs encoding multiple proteasome subunits was observed during proliferation of resting T-cells induced by mitogens such as phytohemagglutinin and interleukin-2. In contrast, in vitro terminal differentiation into monocytic, granulocytic, and erythroid cells of various immature leukemic cell lines, such as HL-60 promyelocytic leukemia cells and K562 erythroleukemia cells, by various inducing agents caused rapid and marked down-regulation of proteasomes expression, independently of the cell type, direction of differentiation, or type of signal. The syntheses of proteasome subunits of 21-31 kDa and their associated components of 35-110 kDa, measured by [35S]methionine incorporation, were much higher in mitogen-activated T-cells and unstimulated HL-60 cells, which grow rapidly, than in resting and differentiated cells, indicating apparent correlations of the mRNA levels of proteasomes with their translational activities. However, immunochemically, no detectable difference in the cellular contents of proteasomes was found in these cells in induced and uninduced states for proliferation and differentiation, suggesting accelerated turnover of proteasomes in rapidly proliferating cells. Inhibition of proteasome expression by an antisense oligodeoxynucleotide for the largest proteasome subunit, C2, caused partial arrest of cell cycle progression of T-lymphocytes, suggesting that up-regulation of proteasomes is indispensable for proliferation of the cells. We also observed that the nuclear fraction of proteasomes increased in proliferating T-cells and that proteasomes moved rapidly between the nucleus and cytoplasm during differentiation of HL-60 cells.
...
PMID:Regulation of gene expression of proteasomes (multi-protease complexes) during growth and differentiation of human hematopoietic cells. 151 42

Baby hamster kidney (BHK) 21/C13 cell proteins, labeled with [35S]methionine, [14C]leucine or [3H]leucine in intact cells, were degraded in soluble, cell-free extracts by an ATP-stimulated process. The stimulatory effect of ATP appeared to require ATP hydrolysis and was mediated to a large extent by ubiquitin. Although the cell extracts contained endogenous ubiquitin, supplementation with exogenous ubiquitin increased ATP-dependent proteolysis by up to 2-fold. Furthermore, antibodies against the E1 ubiquitin conjugating enzyme specifically inhibited both conjugation of [125I]ubiquitin to endogenous proteins and ATP/ubiquitin-dependent proteolysis. Addition of purified E1 to antibody-treated extracts restored conjugation and proteolysis. Proteins containing the amino acid analogues canavanine and azatryptophan were also degraded in vitro by an ATP/ubiquitin-dependent process but at a rate up to 2-fold faster than normal proteins. These results indicate that soluble, cell-free extracts of BHK cells can selectively degrade proteins whose rates of degradation are increased in intact cells. Treatment of cell-free extracts with antibodies against the high molecular weight proteinase, macropain, also greatly inhibited the ATP/ubiquitin-dependent degradation of endogenous proteins. Proteolysis was specifically restored when purified macropain L was added to the antibody-treated extracts. Treatment of cell extracts with both anti-macropain and anti-E1 antibodies reduced ATP/ubiquitin-dependent proteolysis to the same extent as treatment with either antibody alone. Furthermore, proteolysis could be restored to the double antibody treated extracts only after addition of both purified E1 and macropain. These results provide strong evidence for an important role for macropain in the ATP/ubiquitin-dependent degradation of endogenous proteins in BHK cell extracts.
...
PMID:ATP-stimulated degradation of endogenous proteins in cell-free extracts of BHK 21/C13 fibroblasts. A key role for the proteinase, macropain, in the ubiquitin-dependent degradation of short-lived proteins. 184 5

Rat liver proteasome (multicatalytic proteinase complex) is a 20S-ring shaped particle having a molecular mass of 750 kDa, and is composed of at least 13 non-identical components ranging from 21 to 31 kDa in size. We found here that the NH2-terminal residues of all the known 13 components, except for C5, are not reactive to phenylisothiocyanate. Among them, components C2, C3 and C8 are blocked in their NH2-termini with N alpha-acetyl-Met, N alpha-acetyl-Ala, and N alpha-acetyl-Ser, respectively. The NH2-terminal portions of C2, C3, and C8 exhibit sequence similarity to one another, but that of the non-blocked component C5 differs from those of C2, C3, and C8.
...
PMID:The NH2-terminal residues of rat liver proteasome (multicatalytic proteinase complex) subunits, C2, C3 and C8, are N alpha-acetylated. 233 42

The prosomes, a novel type of small RNA-protein complex previously characterized in avian and mammalian cells, were isolated from axolotl (Ambystoma mexicanum) oocytes and identified by sedimentation analysis and protein composition. The prosomal nature of these particles was further ascertained by immunoblot analysis with anti-duck prosome monoclonal antibodies. By in vitro [35S]methionine labelling, de novo synthesis of prosomal proteins could be detected neither during oogenesis nor meiotic maturation. The results obtained by both indirect immunofluorescence and immunoblot analyses demonstrated a dramatic change in the localization of prosomal antigens during oocyte development. They were initially detected in the oocyte cytoplasm, during oocyte growth. At the end of vitellogenesis (stages V-VI), they entered the nucleus (germinal vesicle) and were accumulated there to the highest concentration. During oocyte maturation, after nuclear envelope breakdown, prosomal antigens were found to be localized again in the cytoplasm, until fertilization. No specific localization of prosomal antigens in mature oocytes, unfertilized and fertilized eggs was observed within the oocyte cytoplasm in relation to the cytoplasmic rearrangements leading to grey crescent formation.
...
PMID:Differential cytolocalization of prosomes in axolotl during oogenesis and meiotic maturation. 307 16

Synthesis and release of NAD(P)ase by Neurospora crassa wild type was studied in experiments in which mycelia grown in Vogel minimal medium were transferred to media containing protein as the only carbon source. Several results are presented suggesting that the NAD(P)ase may be induced by the presence of protein in the culture medium. Low concentrations of sucrose or glucose (0.1%), Casamino acids or some amino acids such as methionine, cysteine, phenylalanine and tryptophan strongly repressed the enzyme synthesis. Under induction conditions NAD(P)ase and alkaline protease appeared together in the culture medium. It would appear that NAD(P)ase and alkaline protease are coordinately regulated by a common control mechanism related to carbon catabolism.
...
PMID:Carbon source regulation of nicotinamide adenine dinucleotide (phosphate) glycohydrolase in Neurospora crassa: induction and repression of enzyme synthesis. 623 74

Interactions between protein components of the chemotaxis mechanism in Escherichia coli were investigated by using the cleavable cross-linking reagent, dithiobis(succinimidyl propionate). Two methods were used to allow detection of chemotaxis-specific proteins in intact cells. The first method was to program their synthesis in the presence of [35S]methionine using lambda E. coli hybrid phages which carry the chemotaxis genes. The second method was to label endogenous methyl-accepting chemotaxis proteins (MCP's), with the methyl donor S-adenosyl-L-[methyl-3H]methionine, after permeabilizing the cells with EGTA. Physical associations between proteins were analyzed, after cross-linking, by two dimensional NaDodSO4-polyacrylamide gel electrophoresis. Both labeling methods demonstrate that MCP I and MCP II exist as functional tetramers. Other proteins involved with chemotaxis were found to form dimers and higher polymers. Phage-directed products of cheW, cheX, motA, and cheA formed dimers. CheB and hag products formed multimers. A number of apparent interactions between different gene products were detected as well. Products of cheB, cheW, cheZ, motA, and motB were found to form complexes with other gene products. Included are results consistent with interactions between the products of cheB and cheZ.
...
PMID:Chemotaxis in Escherichia coli: associations of protein components. 644 31

Caulobacter crescentus carries a flagellum and is motile only during a limited time in its cell cycle. We have asked if the biochemical machinery that mediates chemotaxis exists coincident with the cell's structural ability to respond to a chemotactic signal. We first demonstrated that one function of the chemotaxis machinery, the ability to methylate the carboxyl side chains of a specific set of membrane proteins (methyl-accepting chemotaxis proteins, MCPs), is present in C. crescentus. This conclusion is based on the observations that (i) methionine auxotrophs starved of methionine can swim only in the forward direction (comparable to smooth swimming in the enteric bacteria), (ii) a specific set of membrane proteins was found to be methylated in vivo and the incorporated [3H]methyl groups were alkali sensitive, (iii) this same set of membrane proteins incorporated methyl groups from S-adenosylmethionine in vitro, and (iv) out of a total of eight generally nonchemotactic mutants, two were found to swim only in a forward direction and one of these lacked methyltransferase activity. Analysis of in vivo and in vitro methylation in synchronized cultures showed that the methylation reaction is lost when the flagellated swarmer cell differentiates into a stalked cell. In vivo methylation reappeared coincident with the biogenesis of the flagellum just prior to cell division. In vitro reconstitution experiments with heterologous cell fractions from different cell types showed that swarmer cells contain methyltransferase and their membranes can be methylated. However, newly differentiated stalked cells lack methyltransferase activity and membranes from these cells cannot accept methyl groups. These results demonstrate that MCP methylation is confined to that portion of the cell cycle when flagella are present.
...
PMID:Methylation involved in chemotaxis is regulated during Caulobacter differentiation. 657 21

Using a modification of the EGTA treatment of Oishi and Smith [Oishi, M., & Smith, C. L. (1978) Proc. Natl. Acad. Sci. U.S.A. 75, 3569], Escherichia coli cells have been made permeable to S-adenosylmethionine and other related molecules in order to facilitate the study of methylation in chemotaxis. The permeable cells are nonmotile but respond to chemotactic stimuli by reversible methylation of their methyl-accepting chemotactic proteins (MCP I and MCP II) in a manner similar to that of untreated, motile cells. Addition of S-adenosyl-L-[methyl-3H]methionine to the permeable cells specifically labels two proteins, MCP I and MCP II. Methylation of these MCP's is dependent on the presence of wild-type gene products of flaI, flaA, cheB, cheX, tsr, and tar. The extent of methylation of the MCP's is affected by the presence of attractants or repellents: addition of attractant increases the steady-state level of methylation; addition of repellent causes rapid demethylation to a new steady-state level. Methylation is inhibited by the addition of the transmethylase inhibitors A9145C and Sinefungin, which are S-adenosylmethionine analogues, and by S-adenosylhomocysteine.
...
PMID:Methylation of chemotaxis-specific proteins in Escherichia coli cells permeable to S-adenosylmethionine. 677 92

Two-dimensional analysis of tryptic peptides from [35S]methionine-labeled methyl-accepting chemotaxis proteins, MCP I and MCP II, demonstrates a high degree of homology between the two proteins. After the methylation sites were labeled with S-adenosyl-L-methyl-3H]methionine, peptides of three distinct migrations in each protein were found to carry a methyl group. These multiple methylations appear to be responsible in part for the observed multiple banding patterns on sodium dodecyl sulfate/polyacrylamide slab gels.
...
PMID:Structural studies of methyl-accepting chemotaxis proteins of Escherichia coli: evidence for multiple methylation sites. 699 98


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

---