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 ability of some proteins to bind cholesterol was accompanied by a decrease of turbidity of aqueous cholesterol suspensions and correlated with a quantity of arginine residues in them. Maximum clearing of aqueous cholesterol suspensions at the addition of proteins containing equimolar arginine concentrations was observed in the presence of apoproteins E and A-I. Optical rotatory dispersion spectra of apoprotein E, polyarginine and histone H3 have shown the influence of sterol on the secondary structure of apoprotein E only.
Mol Biol (Mosk)
PMID:[The role of the structural organization of apoprotein E in cholesterol binding]. 671 20

The solution proton nuclear magnetic resonance spectrum of the Met-cyano form of sperm whale myoglobin reveals the presence of two sets of comparably intense resonances immediately after reacting the apoprotein with hemin, only one of which corresponds to that of the accepted native protein. Isotope labeling of individual methyl groups of hemin reveals that the methyl assignments differ characteristically in that similar resonance positions for the two components arise from the methyl groups related by a 180 degrees rotation about the alpha-gamma-meso axis. This phenomenon, observed earlier only for myoglobin with modified hemin, dictates that the second protein component in solution immediately after reconstitution must have the heme rotated by 180 degrees about the alpha-gamma-meso axis as compared to that found in the single crystal. The two components in the reconstituted protein equilibrate to yield the spectrum of the native Met-cyanomyoglobin for which there still exists approximately 8% of the minor component. Thus native myoglobin in solution is structurally heterogeneous in the heme pocket. Proton nuclear magnetic resonance spectra of deoxymyoglobin produced from both native and freshly reconstituted protein shown that the heterogeneity is also a property of the physiologically relevant reduced protein forms. It is suggested that, contrary to available X-ray data, heme orientational heterogeneity may be the rule rather than the exception in b-type hemoproteins, and that such disorder must be carefully considered in detailed correlations between structure and function even in native hemoproteins.
J Mol Biol 1983 Aug 25
PMID:Heme orientational disorder in reconstituted and native sperm whale myoglobin. Proton nuclear magnetic resonance characterizations by heme methyl deuterium labeling in the Met-cyano protein. 688 54

Phytochrome is the red/far-red absorbing photoreceptor active in photomorphogenesis, the apoprotein of which is encoded by a small gene family (PHYA, PHYB, PHYC, PHYD and PHYE). A novel phytochrome B-deficient mutant, phyB-103, was isolated from a screen of EMS-mutagenised Arabidopsis M2 seed. phyB-103 carries a G-to-A base substitution at the 5' splice site +1 G nucleotide of intron 1 of PHYB. The phyB-103 PHYB transcript is larger than the wild-type PHYB transcript and DNA sequence analysis showed that the entire intron is retained in the mature PHYB transcript of phyB-103. Thus the phyB-103 G-to-A substitution prevents intron splicing. The retained intron contains within it an in-frame stop codon, and the predicted PHYB-003 apoprotein thus terminates prematurely. phyB-103 is therefore likely to be a null allele of PHYB, consistent with the observation that the phenotype conferred by phyB-103 is as severe as that conferred by previously described phyB null alleles.
Plant Mol Biol 1995 Mar
PMID:Impaired splicing of phytochrome B pre-mRNA in a novel phyB mutant of Arabidopsis. 753 7

We have isolated a gene from a library of nuclear DNA for a chlorophyll a/c-binding protein (named Cac for chl a/c by analogy with Cab for chl a/b) of a chromophyte alga, Giraudyopsis stellifer, and sequenced it. The comparison of the deduced amino acid sequence with other chl a/c- and chl a/b-binding protein sequences shows that structural and functional features, i.e. the arrangement 'en X' of the two A and B transmembrane helices and the putative chl a-binding sites, are shared by both Chlorophyta and Chromophyta. Moreover, in contrast to Chlorophyta, a very strong identity is found among Chromophyta in the C helix suggesting a major function associated to this specific region. Nevertheless, the primary structure of the apoprotein does not seem affected by the pigment composition in Chromophyta. As in the few other examples currently known, we confirm that the cac genes are nuclear-encoded and are part of a multigenic family. Northern blots, performed on poly(A)+ mRNA from G: stellifer, give evidence that the cac gene is light-induced at a transcriptional level and that no expression can be observed in the dark.
Plant Mol Biol 1995 Oct
PMID:Molecular study of a light-harvesting apoprotein of Giraudyopsis stellifer (Chrysophyceae). 757 59

The genes encoding apolipoprotein (apo) E and apoC1 are, together with the gene for apoC2, located in a conserved gene cluster on human chromosome 19q12-13.2 and mouse chromosome 7. Although the significance of apoE as a ligand for receptor-mediated uptake of lipoprotein remnant particles is undisputed, the in vivo function of apoC1 and the possible interaction between apoE and apoC1 in the modulation of plasma cholesterol and triglyceride levels is far from understood. Our strategy to unravel the metabolic relationship between apoE and apoC1 in vivo is to first generate mice deficient in both apolipoproteins, enabling future production of transgenic mice with variable ratios of normal and mutant apoE and apoC1 on a null background. Here we report the creation and characterization of mice deficient in both apoE and apoC1. As these genes are tightly genetically linked, double-deficient mice were obtained by two consecutive rounds of gene targeting in mouse embryonic stem cells. Surprisingly, double inactivation of the Apoe and Apoc1 gene loci as well as single inactivations at either one of these loci were found to affect also the RNA expression levels of the other gene members in the Apoe-c1-c2 cluster. This indicates that targeted insertions are not necessarily neutral for the expression of nearby gene members in a given gene cluster. Homozygous Apoe-c1 knockout mice are hypercholesterolemic, with serum cholesterol levels of 12.5 +/- 4.3 mM compared with 2.9 +/- 0.5 mM in control mice, resembling mice solely deficient in apoE.
Hum Mol Genet 1995 Aug
PMID:Inactivation of Apoe and Apoc1 by two consecutive rounds of gene targeting: effects on mRNA expression levels of gene cluster members. 758 81

pBNiR1, a cDNA clone encoding part of the barley nitrite reductase apoprotein, was isolated from a barley (cv. Maris Mink) leaf cDNA library using the 1.85 kb insert of the maize nitrite reductase cDNA clone pCIB808 as a heterologous probe. The cDNA insert of pBNiR1 is 503 bp in length. The nucleotide coding sequence could be aligned with the 3' end of other higher plant nitrite reductase apoprotein cDNA sequences but diverges in the 3' untranslated region. The whole-plant barley mutant STA3999, previously isolated from the cultivar Tweed, accumulates nitrite after nitrate treatment in the light, has very much lowered levels of nitrite reductase activity and lacks detectable nitrite reductase cross-reacting material due to a recessive mutation in a single nuclear gene which we have designated Nir1. STA3999 has the characteristics expected of a nitrite reductase apoprotein gene mutant. Here we have used pB-NiR1 in RFLP analysis to determine whether the mutation carried by STA3999 is linked to the nitrite reductase apoprotein gene locus Nii. An RFLP was identified between the wild-type barley cultivars Tweed (major hybridising band of 11.5 kb) and Golden Promise (major hybridising band of 7.5 kb) when DraI-digested DNA was probed with the insert from the partial barley nitrite reductase cDNA clone, pBNiR1. DraI-digested DNA from the mutant STA3999 also exhibited a major hybridising band of 11.5 kb after hybridisation with the insert from pBNiR1.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Gen Genet 1995 Jun 10
PMID:The Nir1 locus in barley is tightly linked to the nitrite reductase apoprotein gene Nii. 760 37

The first required step in ecdysteroid (molting hormone) biosynthesis, dietary cholesterol (C) conversion to 7-dehydrocholesterol (7dC) via 7,8-dehydrogenation, is mediated by a microsomal cytochrome-P450 monooxygenase specific to the larval prothoracic gland. A subsequent series of unknown "black-box" oxidations of 7dC result in the unusual ring geometry (cis-A/B) and functionality (6-keto-7-ene-14-alpha-ol) of the ecdysteroids and has been thought to involve the initial formation of alpha-5,6-epoxy-7-dehydrocholesterol (alpha epo7dC). Pharmacological studies indicated that conversion of C to 7dC in prothoracic gland homogenates was strongly and equally inhibited by the isomeric cholesterol substrate analogues alpha- and beta-5,6-epoxycholesterol (alpha- and beta epoC) and alpha- and beta-5,6-iminocholesterol (alpha- and beta iminoC). With respect to the conversion of C to ecdysteroids by disrupted glands, however, the two alpha-isomeric substrates were 10-fold more inhibitory than were their beta-analogues. Indeed, alpha amino C was as active as the non-specific pyrimidyl cytochrome-P450 monooxygenase inhibitor fenarimol that shows moderate toxicity in many insect species. All four cholesterol analogues competitively inhibited cholesterol 7,8-dehydrogenation, but only alpha epoC and possibly alpha iminoC were desaturated to delta 7-products. Although the KmS (and KiS) for all the substrates were similar (1.7-6.0 x 10(-5) M), the Vmax for alpha epoC dehydrogenation was eight-fold higher than that of C, making it a superior substrate for following this reaction in ecdysteroidogenic tissues rich in endogenous C. The 7,8-dehydrogenation of alpha epoC and alpha iminoC by prothoracic glands would produce the potentially reactive intermediates, alpha epo7dC and alpha imino7dC, respectively. They, in turn, could then undergo facile, acid-catalyzed ring-opening to the allylic-stabilized carbo-cation electrophiles. These very reactive, transient species, if formed in the active site of the monooxygenase, would then alkylate either the heme group or the apoprotein of the cytochrome or both, leading to the irreversible inhibition of the enzyme. The present data show that alpha epoC and probably alpha iminoC are mechanism-based suicide inhibitors of the enzyme catalyzing cholesterol 7,8-dehydrogenation and may be the prototypes of a new class of selective insect control agents.
Insect Biochem Mol Biol 1995 Jun
PMID:Stereospecific, mechanism-based, suicide inhibition of a cytochrome P450 involved in ecdysteroid biosynthesis in the prothoracic glands of Manduca sexta. 762

The mouse apolipoprotein D gene was isolated from a brain cDNA library. The nucleotide sequence contains a unique reading frame coding for a protein sharing 79.5% homology with human apoD, 86.2% homology with rabbit apoD and 92.6% homology with rat apoD. The four sequences have two potential asparagine-linked glycosylation sites at residues 45 and 78, and possess the two consensus sequences of the lipocalin family which coincide with the most conserved regions in the four species studied. The distribution of apoD mRNA among mouse organs was determined by Northern blot and quantitative dot blot analysis. The highest levels of mRNA were found in the central nervous system (CNS), namely in the spinal cord, the cerebellum and the brain. Very low concentrations were detected in all the other organs tested. In some organs (spleen, kidney, intestines, heart), a second messenger of lower molecular weight was detected. Gene expression was also measured in rat tissues. As in the mouse, rat CNS was found to be by far the highest expressor of apoD mRNA, in contrast to the rabbit and human. Levels of expression in most mouse and rat organs appeared to be much lower than in the same organs of the rabbit and human. Since apoD is expressed at sites of nerve regeneration as well as apoE, our results raise the question of whether or not the two proteins play a coordinated role in the CNS.
Brain Res Mol Brain Res 1995 Jun
PMID:Molecular characterization and differential mRNA tissue distribution of mouse apolipoprotein D. 763 75

It has previously been shown that baker's yeast trans ketolase has no intersubunit disulfide bonds and is able to dissociate reversibly into subunits at a low apoprotein concentration in solution. By contrast, in the present work it was found that in the molecule of transketolase C (a newly discovered form of the enzyme) subunits are bound to each other by disulfide bonds.
Biochem Mol Biol Int 1994 Nov
PMID:Intersubunit disulfide bonds in the molecule of baker's yeast transketolase. 770

Form A of two previously described human monoclonal anti-riboflavin IgGs, the GAR [Farhangi, M. & Osserman, E. F. (1976) N. Engl. J. Med. 294, 177-183] and DOT [Merlini, G., Bruening, R., Kyle, R. & Osserman, E. F. (1990) Mol. Immunol. 27, 385-394], has been characterized in terms of binding properties and primary structure. Both forms were isolated as immunocomplexes with bound riboflavin and gave a reconstitutable apoprotein. The riboflavin-reconstituted IgGs showed a similar visible absorption spectrum, with a marked resolution of the 445-nm band and a ratio 445-nm/370-nm peaks of 1.13 for DOT and 1.19 for GAR. Both proteins bind riboflavin, FMN and FAD with a molar ratio ligand/protein of 2:1. DOT and GAR share a very similar affinity for the flavinic ligands; the Kd values for riboflavin and FMN are in the range 1 nM; that for FAD is an order of magnitude higher. DOT and GAR do not form an adduct between the nucleophilic group sulfite and the N(5) position of the flavin, and do not stabilize any flavinic semiquinone during reduction with the xantine/xantine oxidase benzylviologen system. The primary structure of fragment antigen binding (Fab) DOT and heavy-chain variable region (VH) GAR determined in the present study and that already known for the light-chain variable region (VL) GAR [Kiefer, C. R., McGuire, B. S., Osserman, E. F. & Garver, F. A. (1983) J. Immunol. 131, 1871-1875] evidenced that the two IgGs are assembled with VL and VH chains of different subgroups; a lambda III/HIII pair in GAR, and a lambda II/HI pair in DOT. Although less similar each other than to the counterparts of the same subclasses, DOT and GAR share an exclusive identity in the VH CDR3 region.
 ...
PMID:Characterization of the two unique human anti-flavin monoclonal immunoglobulins. 773 90


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