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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

p68 is an inducible protein kinase which is believed to be an important factor in the regulation of both viral and cellular protein synthesis. We have produced a monoclonal antibody (TJ4C4) which specifically detects p68, and which can be used to detect this antigen in formalin-fixed, paraffin-embedded tissues. Because p68 plays an important role in cellular protein synthesis, we hypothesized that it may correlate with normal and neoplastic cellular differentiation. One hundred and seventy-seven head and neck squamous cell carcinoma specimens, representing 82 patients, were studied. The relative amount, frequency, and distribution of p68 expression were determined by microscopic evaluation of ABC immunoperoxidase-stained specimens. A spectrum of immunoreactivity was detected in 156 of 177 tumors, as well as within the normal squamous epithelium. Normal, actively proliferating cells, such as the basal layer of squamous epithelium, expressed comparatively little p68. Increased p68 expression was noted to parallel the morphologic features of cellular differentiation. In neoplastic tissue, p68 expression also increased with the degree of cellular differentiation. These data demonstrate that the expression of p68 parallels the degree of cellular differentiation in squamous cell carcinoma of the head and neck region, as well as within normal squamous mucosa. Therefore, p68 may provide an objective biologic measure of cellular differentiation which does not depend on morphologic features.
Virchows Arch B Cell Pathol Incl Mol Pathol 1993
PMID:Correlation of the expression of double-stranded RNA-dependent protein kinase (p68) with differentiation in head and neck squamous cell carcinoma. 810 99

Regulatory properties of estrogen receptor (ER) result from the existence of functional domains within its primary structure. Thus, A/B and C domains which are rich in tyrosyl residues control gene expression while the E domain confers estrogen binding capacity. Hydroxylapatite (HAP) is known to adsorb ER. Scatchard plot analysis of [3H]estradiol binding patterns of HAP batches to which cytosolic ER had been adsorbed revealed that AB and/or C domains are mainly responsible for this property. Thus, treatment of these batches with the tyrosine reagent tetranitromethane (TNM) led to a dramatic release of adsorbed receptors. This did not occur with ER preparations devoid of exposed ABC domains obtained by selective immunoextraction with H-226 anti-ER monoclonal antibody prior to HAP assay. KC1 treatment (500 mM) of HAP batches also led to a release of bound receptors especially those devoid of exposed ABC domains. Such binding characteristics were also found with full length and truncated ERs produced in yeast: the full length receptor strongly interacted with HAP while the truncated receptor devoid of AB and C domains displayed only a weak adsorption. Additional investigation revealed that estradiol binding to cytosolic ER does not modify its reactivity towards TNM.
J Steroid Biochem Mol Biol 1994 Jan
PMID:Importance of A/B and C domains of the estrogen receptor for its adsorption to hydroxylapatite. 813 2

Streptomyces longisporoflavus produces the polyketide-polyether antibiotic, tetronasin, which acts as an ionophore and depolarizes the membrane of bacteria sensitive to the drug. A genomic library of S. longisporoflavus DNA was cloned in Streptomyces lividans and screened to identify tetronasin-resistance determinants. The inclusion of 0.2M NaCl in the growth medium with tetronasin markedly improved the sensitivity of the screen. Two different resistance determinants, designated tnrB (ptetR51) and tnrA (ptetR11) respectively, were identified. The determinant tnrB (ptetR51) but not tnrA (ptetR11), also conferred resistance to tetronasin when cloned into Streptomyces albus. The tnrB determinant was further localized, by subcloning, to a 2.8 kb KpnI fragment. DNA sequence analysis of this insert revealed one incomplete and two complete open reading frames (ORFs 1, 2 and 3). The deduced sequence of the gene product of ORF2 (TnrB2) revealed significant similarity to the ATP-binding domains of the ABC (ATP binding cassette) superfamily of transport-related proteins. The adjacent gene, ORF3, is translationally coupled to ORF2 and would encode a hydrophobic protein (TnrB3) with six transmembrane helices which probably constitutes the integral membrane component of the transporter. The mechanism of tetronasin resistance mediated by tnrB is probably an ATP-dependent efflux system.
Mol Microbiol 1994 Feb
PMID:An ABC-transporter from Streptomyces longisporoflavus confers resistance to the polyether-ionophore antibiotic tetronasin. 819 49

Within the capsule gene complex (cps) of Neisseria meningitidis two functional regions B and C are involved in surface translocation of the cytoplasmically synthesized capsular polysaccharide, which is a homopolymer of alpha-2,8 polyneuraminic acid. The region-C gene products share characteristics with transporter proteins of the ABC (ATP-binding cassette) superfamily of active transporters. For analysis of the role of region B in surface translocation of the capsular polysaccharide we purified the polysaccharides of region B- and region C-defective Escherichia coli clones by affinity chromatography. The molecular weights of the polysaccharides were determined by gel filtration and the polysaccharides were analysed for phospholipid substitution by polyacrylamide gel electrophoresis and immunoblotting. The results indicate that the full-size capsular polysaccharide with a phospholipid anchor is synthesized intracellularly and that lipid modification is a strong requirement for translocation of the polysaccharide to the cell surface. Proteins encoded by region B are involved in phospholipid substitution of the capsular polysaccharide. Nucleotide sequence analysis of region B revealed two open reading frames, which encode proteins with molecular masses of 45.1 and 48.7 kDa.
Mol Microbiol 1993 May
PMID:Phospholipid substitution of capsular polysaccharides and mechanisms of capsule formation in Neisseria meningitidis. 832 61

Cell adhesion to extracellular matrix molecules such as fibronectin involves complex transmembrane signaling processes. Attachment and spreading of primary fibroblasts can be promoted by interactions of cell surface integrins with RGD-containing fragments of fibronectin, but the further process of focal adhesion and stress fiber formation requires additional interactions. Heparin-binding fragments of fibronectin can provide this signal. The COOH-terminal heparin-binding domain of fibronectin contains five separate heparin-binding amino acid sequences. We show here that all five sequences, as synthetic peptides coupled to ovalbumin, can support cell attachment. Only three of these sequences can promote focal adhesion formation when presented as multicopy complexes, and only one of these (WQPPRARI) retains this activity as free peptide. The major activity of this peptide resides in the sequence PRARI. The biological response to this peptide and to the COOH-terminal fragment may be mediated through cell surface heparan sulfate proteoglycans because treatment of cells with heparinase II and III, or competition with heparin, reduces the response. Treatment with chondroitinase ABC or competition with chondroitin sulfate does not.
Mol Biol Cell 1993 Jun
PMID:A synthetic peptide from the COOH-terminal heparin-binding domain of fibronectin promotes focal adhesion formation. 837 70

The solution structures of the trp-repressor from Escherichia coli in both the liganded (holo-) and unliganded (apo-) form, have been refined by restrained molecular dynamics with simulated annealing using the program XPLOR and additional experimental constraints. The ensemble of refined holorepressor structures have a root-mean-square deviation (r.m.s.d.) of 0.8 A relative to the average structure for the backbone of the dimer core (helices A, B, C, A', B', C') and 2.5 A for the helix-turn-helix DNA-binding domain (helices D and E). The corresponding values for the aporepressor are 0.9 A for the backbone of the ABC-dimer core and 3.2 A for the DE helix-turn-helix. The r.m.s.d. of the average structures from the corresponding crystal structures are 2.3 A for the holorepressor ABC core and 4.2 A for its DE region; 2.3 A for the aporepressor core and 5.5 A for its DE region. The relative disorder of the DNA-binding domain is reflected in a number of experimental parameters including substantially more rapid backbone proton exchange rates, exchange-limited relaxation times and crystallographic B-factors. The stabilizing effect of the L-Trp ligand is evident in these measurements, as it is in the higher precision of the holorepressor structure.
J Mol Biol 1993 Feb 05
PMID:Refined solution structures of the Escherichia coli trp holo- and aporepressor. 843 68

The nucleotide sequence of cosmid B1790, carrying the Rif-Str regions of the Mycobacterium leprae chromosome, has been determined. Twelve open reading frames were identified in the 36716bp sequence, representing 40% of the coding capacity. Five ribosomal proteins, two elongation factors and the beta and beta' subunits of RNA polymerase have been characterized and two novel genes were found. One of these encodes a member of the so-called ABC family of ATP-binding proteins while the other appears to encode an enzyme involved in repairing genomic lesions caused by free radicals. This finding may well be significant as M. leprae, an intracellular pathogen, lives within macrophages.
Mol Microbiol 1993 Jan
PMID:Nucleotide sequence of the first cosmid from the Mycobacterium leprae genome project: structure and function of the Rif-Str regions. 844 28

Fission yeast responded to environmental cadmium by producing a family of small Cd-binding peptides, phytochelatins (PCn). A low molecular weight (LMW) complex essentially composed of PC2, and PC3 was produced and then disappeared gradually in 24 hrs after Cd treatment, which served as a transient form for a temporary but quick relief of Cd in the cytosoL It had been reported that the LMW complex was further transported into the vacuole by an ABC-type protein (HMT1), and a higher molecular weight (HMW) complex was formed in the vacuole. Results from gel filtration chromatography and HPLC analysis showed that the transformation of the LMW to the HMW complex was accompanied with a rearrangement of its PCn component. Besides, the molecular conformation of the HMW complex changed from a relaxed form in the early stage to a more condensed conformation during cell aging. And the transformation of the LMW into the HMW complex by the addition of sulfide in the test tube was demonstrated.
Biochem Mol Biol Int 1995 Aug
PMID:Transformation of cadmium-binding complexes during cadmium sequestration in fission yeast. 853 88

The bacteriocin pediocin PA-1 operon of Pediococcus acidilactici PAC1.0 encompasses four genes: pedA, pedB, pedC and pedD. Transcription of the operon results in the formation of two overlapping transcripts, probably originating from a single promoter upstream of pedA. The major transcript comprises pedA, pedB, and pedC, while a minor transcript encompasses all of these genes and pedD. By deletion analysis and overexpression of pedB in Pediococcus pentosaceus we demonstrate that this gene encodes the pediocin PA-1 immunity protein. Prepediocin is active in Escherichia coli and when pedA was expressed concomitantly with pedD both the precursor and the mature form of pediocin were observed intracellularly. Extracellular pediocin was only detected if both pedC and pedD were present. The N-terminal domains of PedD and a subgroup of bacteriocin ABC-transporters are conserved. Expression of only this domain of PedD in cells producing prepediocin was sufficient for prepediocin processing. From these results we conclude that both PedC and PedD are essential for pediocin transport, and that PedD is capable of processing prepediocin.
Mol Microbiol 1995 Aug
PMID:Functional analysis of the pediocin operon of Pediococcus acidilactici PAC1.0: PedB is the immunity protein and PedD is the precursor processing enzyme. 855 70

Two divergently oriented operons, strXU and strVW, located within the gene cluster for 5'-hydroxystreptomycin (5'-OH-Sm) biosynthesis in Streptomyces glaucescens strain GAL.0 (ETH 22794), were analysed by DNA sequencing and transcription/regulation studies. Three genes, strU and strVW, are conserved in a similar arrangement but in a different location within the str/sts gene cluster of the Sm-producing strain S. griseus N2-3-11. The four putative products resemble NDP-4-ketohexose 3,5-epimerases (StrX, M(r) 20.2 kDa), NAD(P)-dependent oxidoreductases (StrU, 45.6 kDa), and ABC-transporters (StrV, 61.8 kDa; StrW, 63.4 kDa). These genes are apparently involved in the biosynthesis of 5'-OH-Sm because the promoters of both operons are activated in trans by the activator StrR of S. griseus N2-3-11, when cloned in S. lividans 66 TK23. A sequence motif resembling the consensus sequence GTTCGActG(N)11CagTcGAAc for binding of StrR was identified within the intergenic region of strX and strV. Specific binding of StrR to this site was demonstrated by gel retardation assays using purified His*Tag-StrR.
Mol Gen Genet 1996 Apr 10
PMID:The str gene cluster for the biosynthesis of 5'-hydroxystreptomycin in Streptomyces glaucescens GLA.0 (ETH 22794): new operons and evidence for pathway-specific regulation by StrR. 862 39


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