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Xenopus liver ferritin H subunit: cDNA sequence and mRNA production in the liver following estrogen treatment.

In vitro translation of liver mRNA from estrogen-treated Xenopus frogs yields two abundant polypeptides in the range of 20 kDa. DNA clones for one of these translation products were isolated and shown to be complementary to mRNA for the heavy subunit of ferritin. The predicted Xenopus amino acid sequence shares about 86% identity with the ferritin heavy chain from bullfrogs and about 70% identity with the comparable mammalian and avian proteins. Clone identity was confirmed by hybridization selection followed by in vitro translation into translation products of 19.5-20 kDa. The nearly full-length cDNA clone, termed XlferH1, comprises 868 nucleotides plus 22 adenosines of the poly(A) tail, including 134 nucleotides of the 5'-untranslated region, a 528-base coding region for 176 amino acids, and a 206-nucleotide 3'-untranslated region. The clone lacks 22 nucleotides from the 5' end of the mRNA. The level of ferritin mRNA in the liver of estrogen-treated frogs was determined over time. The amount of this mRNA relative to total RNA decreased about 3-fold 14 days after estradiol-17 beta was administered. However, the hormone also elevated total RNA in the liver about 24-fold. Hence, the total ferritin mRNA content of the liver increased to about 8 times its initial amount. This pattern of gene expression was very similar to that for serum retinol binding protein. The estrogen induction of these two mRNAs appeared to parallel the overall stimulation of hepatic RNA synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

Human dioxin-inducible cytosolic NAD(P)H:menadione oxidoreductase. cDNA sequence and localization of gene to chromosome 16.

NAD(P)H:menadione oxidoreductase (NMOR1) is a flavoprotein that catalyzes the two-electron reduction of various redox dyes and quinones. It has been proposed that this enzyme may have a protective effect against cancer caused by quinones and their metabolic precursors. We show that tetrachlorodibenzo-p-dioxin (TCDD) treatment of the human hepatoblastoma cell line Hep-G2 produces a 5-fold induction of NMOR activity. Several overlapping human NMOR1 cDNAs were isolated from a human liver lambda gt 11 expression library, and their composite sequence corresponds to an mRNA of 2448 nucleotides containing a continuous open reading frame encoding a protein of 274 residues (molecular weight, 30,880). The corresponding human NMOR1 mRNA has an unusually long 3'-untranslated region (1679 base pairs) with four potential polyadenylation signals (I-IV) at positions 986, 1460, 1838, and 2419 and a single copy of human Alu repetitive sequence between polyadenylation sites II and III. Southern blot analysis of human genomic DNA suggests the presence of a single NMOR1 gene approximately 10 kilobases (KB) in length. The use of three of the aforementioned polyadenylation signals is likely to account for the three different species (2.7, 1.7, and 1.2 kb) of mRNA hybridizing to NMOR1 cDNA in Hep-G2 cells. Indeed several partial cDNA clones were isolated that corresponded to the mRNA derived by use of the proximal polyadenylation signal. Interestingly, the longest (2.7 kb) mRNA species was induced severalfold by TCDD, whereas the other two mRNAs (1.7 and 1.2 kb) were induced to a much lesser extent by TCDD treatment. The human NMOR1 cDNA and protein are 83 and 85% similar to rat liver cytosolic NMOR1 cDNA and protein, respectively. Southern analysis of DNA from 54 human x mouse and 39 human x hamster somatic cell hybrids shows that the NMOR1 gene resides on human chromosome 16.

Amino Acid Sequence↗

Isolation, characterization, and cDNA sequence of two fatty acid-binding proteins from the midgut of Manduca sexta larvae.

Two abundant fatty acid-binding proteins (MFB1 and MFB2) were isolated from the midgut cytosol of larval Manduca sexta. As isolated, MFB1 and MFB2 were found to contain bound fatty acids in a 1:1 molar stoichiometric ratio. Immunological screening demonstrated that MFB1 and MFB2 were restricted to the midgut in a gradient distribution, with MFB1 more concentrated in the anterior two-thirds of the midgut and MFB2 more concentrated in the posterior two-thirds of the midgut. MFB1 exchanged fatty acid more readily than did MFB2. MFB1 was about 2% and MFB2 about 12% of the cytosolic protein in the midgut. cDNA clones for MFB1 and MFB2 both encode proteins of 131 amino acids that are rich in lysine and acidic residues. Analysis of the amino acid sequence alignment of the MFBs with six mammalian fatty acid-binding proteins revealed a number of shared features: 9 conserved glycines, presumably important in turns of the beta-strands; a basic amino acid in a position corresponding to the residue reported to participate in binding the carboxyl group of the fatty acid (Arg in MFB1 and Lys in MFB2); and conservation of many of the residues important in binding the aliphatic portion of the fatty acid.

Amino Acid Sequence↗

cDNA sequence of a sunflower oleosin and transcript tissue specificity.

Oleosins (oil body membrane proteins) of 20.5 and 18 kDa have been purified from sunflower (Helianthus annuus) seeds and polyclonal antibodies raised against them. The precipitated rabbit immunoglobulin fraction was purified by affinity chromatography on cyanogen bromide-activated Sepharose and specifically recognised polypeptides of 18 and 20.5 kDa in sunflower homogenate and oil body fractions assayed by western blotting. A near-full-length cDNA clone was isolated for the 20.5 kDa oleosin. The 694 bp cDNA contained an open reading frame of 534 bp, followed by an untranslated region of 81 bp and a poly(A) region of 70 bp. The open reading frame encoded a polypeptide of 19.8 kDa. Study of transcript localisation revealed message to be abundant in the embryo during the later stage of development and still present in the dry seed. No signal was observed in RNA prepared from expanding leaves.

Amino Acid Sequence↗

Enhancement of poplar glutaredoxin expression by optimization of the cDNA sequence.

Glutaredoxins are low-molecular-weight oxidore ductases that play an important role in redox regulation in eukaryotic and prokaryotic cells. Because of their low abundance, these proteins are poorly characterized in plants. Furthermore, very poor yields have been obtained with the expression systems prepared so far, and in addition, the recombinant products contain a His-tag which can interfere with the biochemical characterization. In order to obtain more information about those important regulatory proteins in plants, a cDNA coding for an extended glutaredoxin has been introduced into the expression plasmid pET-3d and the resulting construction has been used to transform Escherichia coli strain BL21(DE3) in the presence of plasmid helper pSBET or not. Initially poor or ineffective protein expression has been improved by successively cloning a N-terminus truncated form of the protein, introducing silent mutations both at the 5' and at the 3' ends of the nucleotide sequence, and finally altering the 3' end in order to change the C-terminus amino acid sequence of the protein. The first modifications have allowed us to produce the protein in large amounts but essentially in an insoluble form which could be resolubilized and purified. On the other hand, changing the C-terminus sequence resulted in protein preparations of high purity and in a soluble form. The recombinant proteins were biochemically active and the yield varied between 6 and 14 mg of homogeneous protein per liter of culture.

Amino Acid Sequence↗

Molecular cloning, cDNA sequence, and bacterial expression of human glutamine:fructose-6-phosphate amidotransferase.

Glutamine:fructose-6-phosphate amidotransferase (GFAT) has recently been shown to be an insulin-regulated enzyme that plays a key role in the induction of insulin resistance in cultured cells. As a first step in understanding the molecular regulation of this enzyme the human form of this enzyme has been cloned and the functional protein has been expressed in Escherichia coli. A 3.1-kilobase cDNA was isolated which contains the complete coding region of 681 amino acids. Expression of the cDNA in E. coli produced a protein of approximately 77 kDa and increased GFAT activity 4.5-fold over endogenous bacterial levels. Recombinant GFAT activity was inhibited 51% by UDP-GlcNAc whereas bacterial GFAT activity was insensitive to inhibition by UDP-GlcNAc. On the basis of these results we conclude that: 1) functional human GFAT protein was expressed, and 2) the cloned human cDNA encodes both the catalytic and regulatory domains of GFAT since the recombinant GFAT was sensitive to UDP-GlcNAc. Overall, the development of cloned GFAT molecular probes should provide new insights into the development of insulin resistance by allowing quantitation of GFAT mRNA levels in pathophysiological states such as non-insulin-dependent diabetes mellitus and obesity.

Amino Acid Sequence↗

Molecular cloning of a cDNA sequence for rat malic enzyme. Direct evidence for induction in vivo of rat liver malic enzyme mRNA by thyroid hormone.

Malic enzyme (EC 1.1.1.40) mRNA was partially purified to 12% of total mRNA activity (greater than 150-fold enrichment) from 3-5-3'-triiodo-L-thyronine-carbohydrate-stimulated rat liver by polysome immunopurification followed by oligo(dT)-cellulose chromatography. This preparation was used as the template for synthesis of cDNA on a pBR322-SV40 hybrid plasmid DNA primer which was then circularized with linker DNA and used to transform Escherichia coli. The resulting transformants were screened by in situ differential hybridization using 32P-labeled poly(A+)RNA prepared from uninduced and 3-5-3'-triiodo-L-thyronine-carbohydrate-induced rat livers. Of 750 transformants screened, 6 were found to hybridize differentially; 1 of these, prME, contained an insert of about 1250 base pairs and hybrid-selected an mRNA which directed synthesis of malic enzyme in a cell-free translation system. Using this cDNA as a probe, we demonstrated that the level of malic enzyme mRNA after thyroid hormone treatment was markedly increased and the size of the major malic enzyme mRNA was shown by Northern analysis to be about 2700 nucleotides in length.

Animals↗

cDNA sequence and chromosomal localization of the remaining three human nuclear encoded iron sulphur protein (IP) subunits of complex I: the human IP fraction is completed.

NADH:ubiquinone oxidoreductase (complex I) of the mitochondrial respiratory chain can be fragmented in a flavoprotein (FP), iron-sulfur protein (IP), and hydrophobic protein (HP) subfraction. The IP subfraction is hypothesized to be significant, since it contains important prosthetic groups highly conserved among species. We cloned the cDNA of three remaining human NADH:ubiquinone oxidoreductase subunits of this IP fraction: the NDUFS2 (49 kDa), NDUFS3 (30 kDa), and NDUFS6 (13 kDa) subunits. All presented cDNAs include the complete open reading frame (ORF), which consist of 1392, 795, and 375 base pairs, coding for 463, 264, and 124 amino acids, respectively. The latter show 96, 90, and 83% homology with the corresponding bovine translation products. The 3' untranslated regions (UTR) are complete in all three cDNAs. Polymerase chain reaction performed with DNA isolated from somatic human-rodent cell hybrids containing defined human chromosomes as template gave a human-specific signal which mapped the NDUFS2 and NDUFS3 subunits to chromosomes 1 and 11, respectively. In the case of the NDUFS6 subunit a pseudogene may be present since signals were seen in the lanes containing chromosomes 5 and 6. The NDUFS2 contains a highly conserved protein kinase C phosphorylation site and the NDUFS3 subunit contains a highly conserved casein kinase II phosphorylation site which make them strong candidates for future mutation detection studies in enzymatic complex I-deficient patients.

Amino Acid Sequence↗

The mouse Laf4 gene: exon/intron organization, cDNA sequence, alternative splicing, and expression during central nervous system development.

The cerebral cortex is a tissue with a high degree of neuronal diversity. It consists of six cell layers with a unique set of neuronal subtypes. A crucial step in the process of cortical differentiation is the transition from a mitotically active neuroblast to a postmitotic young neuron. To identify genes involved in the control of this transition, we applied a novel method of cDNA subtraction based on mirror-orientation selection. One of the genes we have identified in our screening proved to be a mouse homolog of the human putative transcription factor LAF4. We identified alternatively spliced forms of mouse Laf4 that encode several forms of putative protein with potentially different transactivation functions. Two forms are expressed mainly during embryogenesis, whereas the other forms are expressed mainly in adults. We have found that Laf4 transcription becomes very quickly upregulated as soon as young cortical neurons leave the ventricular zone (VZ), the cortical-proliferative compartment. This coincides with the initial steps of cortical differentiation. Laf4 becomes downregulated in postnatal cortex, indicating its involvement in the transcriptional regulation of the early steps of cortical differentiation. We have also examined Laf4 expression in the brains of Sey and reeler mutants. Laf4 was downregulated in the lateroventral part of the cerebral cortex and completely lost in the piriform cortex of the Sey mutant embryos. We also compared its expression during central nervous system development with that of its closest homolog, Fmr2, a gene implicated in mental retardation in humans.

Alternative Splicing↗

cDNA sequence of the lymphotoxin beta chain from a marsupial, Macropus eugenii (Tammar wallaby).

In humans and mice, the lymphotoxin (LT) complex is a heterotrimer that consists of alpha (LT-alpha) and beta (LT-beta) chains, predominantly in the ratio 1:2 (LT-alpha:LT-beta). LT-beta is a type II membrane-bound protein that anchors the complex to the surface of activated lymphocytes and, in gene targeting experiments in mice, has been shown to be crucial for normal lymphoid organogenesis. However, a similar role for LT in noneutherian mammals has not yet been established. Indeed, there has been no previous evidence for the existence of LT in noneutherian species. We have isolated, by rapid amplification of cDNA ends on mammary lymph node cDNA, the transcript coding for LT-beta from the tammar wallaby, Macropus eugenii. This constitutes the first report of an LT component from a marsupial and hence from a noneutherian mammal. The predicted amino acid sequence encoded by this transcript shares 63% and 46% sequence identity with mouse and human LT-beta, respectively.

Amino Acid Sequence↗

cDNA sequence analysis and expression of kappa-bungarotoxin from Taiwan banded krait.

The cDNAs encoding kappa-bungarotoxin was constructed from the cellular RNA isolated from the venom glands of Bungarus multicinctus by reverse transcription-polymerase chain reaction. A high degree of nucleotide sequence homology was observed between kappa-bungarotoxin and other kappa-neurotoxins. The kappa-bungarotoxin was subcloned into the expression vector pET32a(+) and transformed into BL21(DE3) E. coli strain. The recombinant toxin was expressed as a fusion protein. Recombinant kappa-bungarotoxin was separated from the fused protein by cleavage with CNBr and purified by reversed phase high performance liquid chromatography. In addition to kappa-bungarotoxin, the cDNA fragment encoding kappa3-bungarotoxin was also found in the cDNA mixtures prepared from the cellular RNA of the venom glands of the same snake. This result suggests that the venom glands of Taiwanese B. multicinctus should secrete at least two kinds of kappa-neurotoxins.

Amino Acid Sequence↗

cDNA sequence and bacterial expression of mouse liver sterol carrier protein-2.

Sterol carrier protein-2 (SCP-2) is an intracellular protein of Mr 13,096. In vitro studies have shown that it is involved in the transport and metabolism of cholesterol. This protein is believed to participate in these activities by forming a stoichiometric complex with the sterol. Because these activities occur in different intracellular locations, i.e. mitochondria, peroxisomes, and cytosol, it can be predicted that SCP-2 targets to these sites. In this report we show that a mouse cDNA (785 base pairs) encodes a precursor form of SCP-2 containing a N-terminal presequence and an additional C-terminal residue. These additional amino acid residues are found in proteins targeted to the mitochondria and peroxisomes, respectively. These signals are not found in SCP-2 purified from rat liver cytosol which is believed to be a cytosolic form. Northern analysis shows that there are four species of mRNA which hybridize to a SCP-2-specific probe at 1.0, 1.7, 2.2, and 2.9 kilobases. Southern analysis shows that the gene is distributed over a large amount of DNA or that there are multiple genes. We have cloned the cytosolic/peroxisomal form of mouse SCP-2 into the Escherichia coli expression vector pKK233-2 and have expressed and purified recombinant mouse SCP-2, Mr 13,034. The purified recombinant SCP-2 is immunoreactive to rabbit anti-rat SCP-2 antibody. It also has biological activity equivalent to homogeneous rat liver SCP-2 in stimulating the microsomal conversion of 7-dehydrocholesterol to cholesterol and in the esterification of cholesterol by acyl-CoA cholesterol acyltransferase by rat liver microsomes.

Amino Acid Sequence↗

Porcine dentin matrix protein 1: gene structure, cDNA sequence, and expression in teeth.

Dentin matrix protein 1 (DMP1) is an acidic non-collagenous protein that is necessary for the proper biomineralization of bone, cartilage, cementum, dentin, and enamel. Dentin matrix protein 1 is highly phosphorylated and potentially glycosylated, but there is no experimental data identifying which specific amino acids are modified. For the purpose of facilitating the characterization of DMP1 from pig, which has the advantage of large developing teeth for obtaining protein in quantity and extensive structural information concerning other tooth matrix proteins, we characterized the porcine DMP1 cDNA and gene structure, raised anti-peptide immunoglobulins that are specific for porcine DMP1, and detected DMP1 protein in porcine tooth extracts and histological sections. Porcine DMP1 has 510 amino acids, including a 16-amino acid signal peptide. The deduced molecular weight of the secreted, unmodified protein is 53.5 kDa. The protein has 93 serines and 12 threonines in the appropriate context for phosphorylation, and four asparagines in a context suitable for glycosylation. Dentin matrix protein 1 protein bands with apparent molecular weights between 30 and 45 kDa were observed in partially purified dentin extracts. In developing teeth, immunohistochemistry localized DMP1 in odontoblasts and the dentinal tubules of mineralized dentin and in ameloblasts, but not in the enamel matrix.

Amino Acid Sequence↗

cDNA sequence, genomic organization, and evolutionary conservation of a novel gene from the WAGR region.

A new gene (239FB) with predominant and differential expression in fetal brain has recently been isolated from a chromosome 11p13-p14 boundary area near FSHB. The corresponding mRNA has an open reading frame of 294 amino acids, a 3' untranslated region of 1247 nucleotides, and a highly GC-rich 5' untranslated region. The coding and 3' UT sequence is specified by 6 exons within nearly 87 kb of isolated genomic locus. The 5' end region of the transcript maps adjacent to the only genomically defined CpG island in a chromosomal subregion that may be associated with part of the mental retardation of some WAGR (Wilms tumor, aniridia, genitourinary anomalies, and mental retardation) syndrome patients. In addition to nucleotide and amino acid similarity to an EST from a normalized infant brain cDNA library, the predicted protein has extensive similarity to two Caenorhabditis elegans polypeptides of, as yet, unknown function. The 239FB locus is, therefore, likely part of a family of genes with two members expressed in human brain. The extensive conservation of the predicted protein suggests a fundamental function of the gene product and will enable evaluation of the role of the 239FB gene in neurogenesis in model organisms.

Amino Acid Sequence↗

Construction and characterization of a retroviral vector demonstrating efficient expression of cloned cDNA sequences.

We describe the construction and properties of a retroviral expression vector, designated pMV-7, designed to transfer unselected cDNAs and produce their encoded proteins in recipient cells. The vector is flanked by the long terminal repeats (LTRs) of the Moloney murine sarcoma virus (MSV) and contains the selectable drug resistance gene neo under the regulation of the herpes simplex virus (HSV) thymidine kinase (tk) promoter. Unique Eco RI and Hind III sites facilitate the introduction of sequences whose transcription is regulated by the 5' LTR. We have inserted cDNAs encoding: (i) the human lymphocyte antigen T4, (ii) the human lymphocyte antigen T8, and (iii) the murine hypoxanthine-guanine phosphoribosyl transferase (HPRT), into the pMV-7 vector. These constructions were used to transduce recipient cells to the neo+ phenotype. In each case, functional assays demonstrated that 65-92% of the neo+ clones produced the appropriate protein encoded by its corresponding cDNA. These clones were characterized further by analyzing the expression of vector-regulated transcripts. The neo+T4+ clones expressed a single full-length LTR-to-LTR transcript as detected by a T4 probe. The neo+T8+ clones, however, expressed both a full-length LTR-to-LTR transcript and an additional smaller transcript as detected by a T8 probe. This smaller transcript probably resulted from the utilization of cryptic signals which control 3' RNA processing. Furthermore, all of the neo+ clones expressed a transcript that initiated from the tk promoter, contained the neo gene, and used polyadenylation signals provided by the 3' LTR. Thus, the pMV-7 vector is capable of high-efficiency transfer and high-frequency expression of the cDNA-encoded protein.

Animals↗

Induction and cDNA sequence of inducible nitric oxide synthase from canine aortic smooth muscle cells.

An inducible isoform of nitric oxide synthase (type II, iNOS) is expressed in cardiac and vascular smooth muscle in response to inflammatory cytokines. The dog is an important large animal used for cardiovascular research including effects of exercise, heart failure, and allograft rejection. However, molecular probes for iNOS developed in other mammals have not been reliable for the study of iNOS induction in canine vascular smooth muscle. Experiments were designed to develop a molecular probe for canine iNOS. Smooth muscle cells were isolated from canine aortas. The cells (passages 3-10) were incubated for 1, 3, 6, 12, 24, 48, or 72 h in the absence and presence of Escherichia coli lipopolysaccharide (LPS) to induce iNOS. Total RNA was isolated from the cells using standard techniques. RT-PCR with primers against conserved regions of all known iNOS enzyme was used to clone the iNOS cDNA. RT-PCR showed a single band only from cells treated with LPS. Cloned cDNA from cultured canine aortic smooth muscle cells has 84% homology to human, 81% to rat, and 81% to mouse iNOS gene. Identification of the cDNA for canine iNOS will be useful in the study of differential, transcriptional regulation of inducible (type II) compared with constitutive endothelial (type III) NOS in canine studies of allograft rejection and cardiovascular disease.

Amino Acid Sequence↗

Purification, cDNA sequence, and tissue distribution of rat uroguanylin.

Guanylin, a peptide purified from rat jejunum, is thought to regulate water and electrolyte balance in the intestine. We show here, using a combination of Northern blots, Western blots, and functional assays, that guanylin and its receptor (GCC) are not distributed in parallel within the rat intestine. To investigate the possibility that there might be a second intestinal peptide that serves as a ligand for GCC, we assayed tissue extracts for the ability to stimulate cyclic GMP synthesis in a GCC-expression cell line. Duodenal extracts display a peak of biological activity that is not present in colon and that does not comigrate with guanylin or proguanylin. The activity co-purifies with a novel peptide (TIATDECELCINVACTGC) that has high homology with uroguanylin, a peptide initially purified from human and opossum urine. A rat uroguanylin cDNA clone was found to encode a propeptide whose C-terminus corresponds to our purified peptide. Northern blots with probes generated from this clone reveal that prouroguanylin mRNA is strongly expressed in proximal small intestine, but virtually absent from colon, corroborating our biochemical measurements. Taken together, these studies demonstrate an intestinal origin for uroguanylin, and show that within the intestine its distribution is complementary to that of guanylin.

Amino Acid Sequence↗

Porcine N-acetylgalactosamine 6-sulfatase (GALNS) cDNA sequence and expression in developing teeth.

Mucopolysaccharidosis type IVA (Morquio A syndrome, MPS IVA) is a rare, autosomal recessive disorder with a prevalence of 1 in 170,000 live births. It is caused by a deficiency of N-acetylgalactosamine 6-sulfatase (GALNS), a lysosomal hydrolase encoded by a gene on human chromosome 16q24.3. Mucopolysaccharidosis type IVA is the only known MPS that is associated with structural defects in dental enamel. GALNS cleaves the sulfate group from N-acetylgalactosamine 6-sulfate and galactose 6-sulfate, which are specifically found in keratan sulfate and chondroitin 6-sulfate. A pathologic absence of GALNS activity results in the accumulation of these glycosaminoaglycans in the urine and in the lysosomes of tissues that turn them over. There is currently no animal model for MPS IVA. To learn more about how a GALNS deficit could lead to enamel defects, we have cloned and characterized a full-length pig GALNS cDNA. GALNS mRNA was localized in developing teeth by in situ hybridization, Northern blot, and reverse-transcription polymerase chain reaction analyses, while GALNS substrates were localized using immunohistochemistry. We report that secretory ameloblasts were positive for GALNS mRNA, as well as for keratan sulfate and chondroitin 6-sulfate. We conclude that enamel defects associated with the loss of GALNS activity in persons with MPS IVA are likely to result from the pathological accumulation of keratan sulfate and chondroitin 6-sulfate in the lysosomes of secretory stage ameloblasts.

Amino Acid Sequence↗