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At least 19 recordsLinked to original sources
PubMed1987

Structural and functional characterization of a Dictyostelium gene encoding a DIF inducible, prestalk-enriched mRNA sequence.

The pDd56 mRNA sequence is highly enriched in prestalk over prespore cells and is inducible by DIF, the putative Dictyostelium stalk-specific morphogen. We show that the pDd56 gene is composed of forty one copies of a twenty four amino acid, cysteine rich repeat. This is highly homologus to a repeat which we have previously shown to compose the major fraction of the pDd63 mRNA, another DIF inducible, prestalk-enriched sequence. The predicted pDd56 protein contains a putative signal peptide but does not appear to contain a transmembrane segment. In combination these features suggest it to be an extrinsic protein and we confirm this elsewhere by showing that the pDd56 gene encodes a known, extracellular protein of the stalk. The pDd56 mRNA is dependent upon exogenous DIF for its accumulation. We show that this control is exerted at the transcriptional level and that a restriction fragment containing 1.7Kb of upstream sequence directs temporally-regulated expression of the gene.

Amino Acid Sequence↗
PubMed1987

Two distinct classes of prestalk-enriched mRNA sequences in Dictyostelium discoideum.

We have isolated cDNA clones derived from three mRNA sequences which are inducible by DIF, the putative stalk-specific morphogen of Dictyostelium. The three mRNA sequences are selectively expressed in cells on the stalk cell pathway of differentiation and we have compared them with previously characterized prestalk-enriched mRNA sequences. We find these latter sequences are expressed without a dependence on DIF, are much less highly enriched in prestalk over prespore cells and are expressed earlier during development than the DIF-inducible mRNA sequences. We propose two distinct mechanisms whereby a mRNA may become enriched in prestalk cells. An apparently small number of genes, represented by those we have isolated, is inducible by DIF and accumulates only in prestalk cells. We suggest that a second class of prestalk-enriched mRNA sequences are induced by cAMP to accumulate in all cells during aggregation and then become enriched in prestalk cells by selective loss from prespore cells.

Base Sequence↗
PubMed1979

Inserts within the mRNA sequence on the 15 S globin mRNA precursor from chicken.

[3H]Uridine pulse-labelled nuclear RNA of chicken immature red blood cells contains two RNA species with globin coding sequences sedimenting at 9 S and 15 S, the latter representing most probably the precursor to 9 S globin mRNA. Whether the globin mRNA sequence on the 15 S precursor is interrupted by interspersed sequences was investigated by hybridization of labelled nuclear 15 S RNA with an excess of unlabelled globin complementary DNA. After degradation of nonhybridized RNA by RNAase A the enzyme was removed by proteinase K and a subsequent phenol extraction. The complementary DNA hybrids were melted and the complementary DNA degraded by DNAase I. For the separation of complementary DNA protected RNA polyacrylamide gel electrophoresis in formamide was used. Three RNA fragments with approximately 320, 200 and 120 nucleotides were found in the case of the 15 S RNA, whereas only one 650-700 nucleotide fragment was detected when the same procedure was carried out with nuclear 9 S RNA. This means, that the chicken 15 S globin mRNA precursor contains at least two inserts within the mRNA sequence, which originate presumably by transcription of a gene with intervening sequences.

Animals↗
PubMed1976

Globin mRNA sequences in polyadenylated and nonpolyadenylated nuclear precursor-messenger RNA from avian erythroblasts.

Nuclear RNA from immature duck erythrocytes was fractionated into polyadenylated and nonpolyadenylated fractions, and globin mRNA sequences were determined by hybridization to DNA complementary to globin mRNA. 80--90% of labeled nuclear RNA is found to be nonpolyadenylated, and 70--80% of the globin mRNA sequences present in the nucleus are found in nonpolyadenylated molecules. These data suggest that polyadenylation does not specifically select for globin mRNA sequences. The nonpolyadenylated globin mRNA sequences present in the nucleus are found mostly in molecules of small size, close to the size of polyribosomal globin mRNA, suggesting that polyadenylation is a later event in globin mRNA formation.

Animals↗
PubMed1975

Induction of ovalbumin mRNA sequences by estrogen and progesterone in chick oviduct as measured by hybridization to complementary DNA.

A complementary DNA synthesized from ovalbumin mRNA was used in hybridization experiments to study the early effect of estrogen and progesterone on the accumulation of ovalbumin mRNA sequences in the chick oviduct. Chicks treated with estrogen withdrawn from the hormone maintain a steady level of 60 molecules of ovalbumin mRNA per tubular gland cell, at least 80% of which are localized in the cytoplasm. After estrogen administration, there is a 3- to 4-hour lag before a rapid increase in the number of ovalbumin mRNA sequences and a parallel increase in ovalbumin synthesis. Progesterone causes a more rapid increase in both ovalbumin mRNA sequences and ovalbumin synthesis with a lag period of only 90 min. The hybridization results demonstrate that both estrogen and pregesterone affect the amount of ovalbumin mRNA per cell. The 3-hour lag period seen with estrogen appears to be caused by some event after the binding of the estrogen receptor to chromatin but prior to change in the rate of transcription of the ovalbumin gene.

Animals↗
PubMed1985

Developmental changes in the pattern of larval beta-globin gene expression in Xenopus laevis. Identification of two early larval beta-globin mRNA sequences.

We have analysed beta-globin mRNA sequences in total RNA extracted from embryos and tadpoles of Xenopus laevis at different stages of development and we have identified the most abundantly transcribed beta-globin mRNA (beta T1). The entire nucleotide sequence of a cDNA clone corresponding to this mRNA is known. We have now identified the gene corresponding to this mRNA and we have determined the nucleotide sequences of its immediate 5'-flanking region. Using a DNA fragment from within the coding region of the cloned beta T1 cDNA we show, by primer extension analysis, that beta T1 mRNA is first detectable at stage 28-32 of development. This is the time at which the first presumptive erythropoietic tissue, the ventral blood island, becomes observable histologically. We show that two minor beta-globin genes, distinct from beta T1, are expressed during early stages of development, and that their expression ceases shortly after the beginning of the feeding stage. We term these two early larval genes beta E1 and beta E2. A third minor beta-globin gene is expressed during early development but, unlike beta E1 and beta E2, it is also expressed throughout subsequent larval development. We term this gene beta T2 and show that it corresponds to a gene previously termed beta LII. Finally, using a primer derived from the major adult beta-globin gene (beta 1), we have analysed the accumulation of the major adult beta-globin mRNA during larval development, and we show that this sequence does not accumulate to any significant level before metamorphosis.

Animals↗
PubMed1991

Bovine lactoferrin mRNA: sequence, analysis, and expression in the mammary gland.

The mRNA sequence for bovine lactoferrin expressed in the mammary gland was determined by sequencing three over lapping cDNA clones and by direct sequencing of the mRNA. The mRNA (2351 bases) codes for a 708 amino acid protein with a 19 amino acid signal peptide immediately preceding a sequence identical to the N-terminal 40 amino acids reported for bovine lactoferrin. A putative destabilizing sequence (AUUUA) was identified in the 3'-untranslated region. The nucleic acid sequence and deduced amino acid sequence are highly homologous with other transferrin family members. Lactoferrin mRNA concentrations in bovine mammary tissue were quite low two days before parturition and during lactation but were high three days after the cessation of milking, a sharp contrast from the pattern of regulation of the other milk proteins.

Amino Acid Sequence↗
PubMed1991

An analysis of vertebrate mRNA sequences: intimations of translational control.

Five structural features in mRNAs have been found to contribute to the fidelity and efficiency of initiation by eukaryotic ribosomes. Scrutiny of vertebrate cDNA sequences in light of these criteria reveals a set of transcripts--encoding oncoproteins, growth factors, transcription factors, and other regulatory proteins--that seem designed to be translated poorly. Thus, throttling at the level of translation may be a critical component of gene regulation in vertebrates. An alternative interpretation is that some (perhaps many) cDNAs with encumbered 5' noncoding sequences represent mRNA precursors, which would imply extensive regulation at a posttranscriptional step that precedes translation.

Animals↗
PubMed1978

Cleavage of pre-mRNA sequences by ribonucleases bound to nuclear RNP particles of rat liver.

The 30S nuclear RNP particles from rat liver have been shown to split the double-stranded- (ds) and single-stranded (ss) sequences of nuclear pre-mRNA. Experiments performed in vitro have demonstrated that 1) a 5'-exonuclease and an endonuclease specific for double-stranded pre-mRNA sequences exist in the 30S pre-mRNP particles; 2) in dsRNA monophosphorylated 5'-termini arose in the course of incubation with 30S RNP and most of the products remained double-stranded. The analysis of terminal pNp nucleotides revealed a relatively high ratio of pPyp in the cleaved dsRNA, whereas the nucleosides in 5'-terminal pNp of ssRNA showed nearly random distribution. Our results provide a possible explanation for the appearance of pNp termini during the processing of nuclear pre-mRNA of mammalian cells.

Animals↗
PubMed1986

A low-molecular-weight RNA from mouse ascites cells that hybridizes to both 18S rRNA and mRNA sequences.

A low-molecular-weight RNA species from mouse ascites cells has been selected and purified by its intermolecular RNA X RNA hybridization capabilities. This 4.5S RNA is able to base pair with poly(A)+ mRNA sequences and with 18S rRNA. Melting experiments have shown that the intermolecular hybrids formed with this complementary low-molecular-weight RNA are of comparable stability to other RNA X RNA interactions. Analysis has shown that this hybridizing RNA is 87 nucleotides long and has an unusual sequence structure. Located near the 3' terminus is an alternating pyrimidine dinucleotide region of UUCCUUCCUU. This region along with the 3'-adjacent nucleotides form a 14-nucleotide sequence that exhibits perfect complementarity with 18S rRNA. An additional region of 10 nucleotides at the 3' terminus is perfectly homologous to a similarly located sequence in 5.8S rRNA. An obvious RNA polymerase III binding site is not found internally in this low-molecular-weight RNA sequence. The complementary and homologous character of hybridizing RNA with respect to rRNA and mRNA sequences suggests a potential regulatory role for this RNA in the coupling of ribosome and mRNA functions.

Animals↗
PubMed1979

Declining procollagen mRNA sequences in chick embryo fibroblasts infected with rous sarcoma virus. Correlation with procollagen synthesis.

Chick cells infected with Rous sarcoma virus are characterized by a wide variety of changes known collectively as transformation. Among these are decreases in the level of procollagen biosynthesis and in the level of procollagen mRNA. In this communication, we examine the time course of the decrease in procollagen biosynthesis, as measured by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and collagenase assay, and compare it with the decrease in procollagen mRNA sequences measured by hybridization to a complementary DNA. Procollagen biosynthesis and procollagen mRNA sequences decrease simultaneously after infection. Even the initial decrease in procollagen biosynthesis, therefore, is due to a decline in the level of procollagen mRNA.

Animals↗
PubMed1976

Detection of mRNA sequences in nuclear 30S ribonucleoprotein subcomplexes.

RNA from nuclear 30S ribonucleoprotein (RNP) complexes of mouse ascites cells has been shows to contain sequences homologous to poly(A) + mRNA by its ability to hybridize with complementary DNA prepared from poly(A) + mRNA template. Analysis of the hybridization kinetics of poly(A) + mRNA with its own complementary DNA revealed several abundancy classes. The total complexity of poly(A) + mRNA from ascites cells was estimated to be approximately 30,000 sequences of average molecular weight (6 X 10(5)). When the hybridization reaction of 30S RNP-RNA with mRNA-specific cDNA was compared to the homologous reaction the majority, and most probably all, of the poly(A) + mRNA sequences were found to be present in the RNA. The kinetics of hybridization suggest that 10-15% of the RNA in this RNP complex is homologous to poly(A) + mRNA. The 30S RNP subcomplexes therefore contain nuclear poly(A) + mRNA sequences as well as the bulk of heterogeneous RNA.

Base Sequence↗
PubMed1985

mRNA sequence predictions from homologous protein sequences.

A model has been developed that permits the prediction of mRNA nucleic acid sequence from the sequences of the translated proteins. The model relies on the information obtained from the comparison of protein sequences in related species to reduce the number of possible codons for those amino acids where mutations are observed. The predictions so obtained have been tested by applying the model to proteins whose mRNA sequences are known. The model's predictions have been found to be 100% accurate if three or more different amino acids are known at a given position and if the protein sequences are restricted to relatively closely related species (within the same class). The use of this model may permit a reduction of the mRNA sequence degeneracy and therefore be helpful in the synthesis of cDNA probes or for the prediction of restriction endonuclease sites. Computer programs have been developed to ease the use of the model.

Amino Acid Sequence↗
PubMed1986

Multihormonal regulation and kinetics of induction of a hepatic mRNA sequence which is slowly responsive to triiodothyronine.

In contrast to the rapid response of mRNA-S14 which occurs within 20 min after L-triiodothyronine (T3) administration, the induction of other rat hepatic mRNA sequences exhibits a lag time of several hours. We have studied the induction of mRNA-S11 which codes for a protein of pI 6.1 and an Mr of 22,500 as a model of such a slowly responsive gene. In addition to T3, both glucocorticoids and growth hormone regulate the expression of this gene. For each of these stimuli, the response exhibits a lag time of approximately 6 h. Following this lag time, there is a linear increase in the level of mRNA-S11 induced by a single maximal dose of T3, dexamethasone, and growth hormone to levels of 15-, 6-, and 3-fold, respectively, in excess of the hypothyroid base-line levels. The similarity in the lag time and the differences in maximal responses effectively argues against the possibility that the effect of one hormone is mediated exclusively by a change in the secretion or metabolism of another. Support for a direct action of T3 and glucocorticoids on the hepatic cell comes from the observation that these hormones stimulate mRNA-S11 in rat hepatocytes under primary culture. The increases in in vitro nuclear transcription measured following T3 and dexamethasone administration were clearly insufficient to account for the observed increases in mRNA. Furthermore, the hormonal induction of mRNA-S11 was promptly abrogated by cycloheximide (10 mg/kg) injected 6 h after the administration of T3 or dexamethasone at the time of the expected mRNA increase. The post-transcriptional control of the mRNA-S11 and its sensitivity to cycloheximide are similar to previously documented responses of the rapidly induced mRNA-S14 and suggest for both sequences a requirement for ongoing synthesis of rapidly turning over proteins. We speculate that the lag time of response of a given gene to T3 or glucocorticoid may be an intrinsic characteristic of the gene and may represent a common set of molecular events involved in the activation of that gene by diverse stimuli.

Animals↗
PubMed1985

Translational control of the circadian rhythm of liver sterol carrier protein. Analysis of mRNA sequences with a specific cDNA probe.

The striking changes in amount of rat liver SCP (sterol carrier protein) during a 24-h dark-light cycle are due to alterations in the relative synthetic rate of SCP. However, functional SCP mRNA, measured by a cell-free translational assay, does not fluctuate in the dark-light cycle. Since cell-free translational assays do not always reflect the actual abundance of an mRNA molecule, a specific cDNA hybridization assay was used to directly quantitate SCP mRNA sequences. The cDNA probe was selected from a rat liver library by hybridization to a mixture of synthetic oligonucleotides containing a portion of the sequence of SCP mRNA. The relative amount and size distribution of the SCP mRNA species (approximately 700-800 nucleotides) does not change during the diurnal cycle. To explore possible mechanisms of this translational control, the polysomal distribution of SCP mRNA was compared at the maximum and minimum points of SCP synthesis. No significant amounts of SCP mRNA were present in nonpolysomal ribonucleoprotein particles. Furthermore, no alteration in the relative level of SCP mRNA associated with polysomes or in polysome size occurs at the maximum and minimum points of SCP synthesis. Thus, changes in total SCP mRNA levels or its polysomal distribution cannot account for the diurnal variation in SCP synthesis.

Animals↗
PubMed1992

Binding of Xenopus oocyte masking proteins to mRNA sequences.

It has been shown previously that maternal mRNA, synthesized and stored in growing oocytes, is stabilized and blocked from translation through various mechanisms including restricted polyadenylation and the binding of proteins to 3' regulatory elements. In addition to binding sequence-specific proteins, the bulk of stored mRNA is packaged with a set of 'masking' proteins, the most abundant of which are the phosphoproteins pp56 and pp60. In this report these proteins are shown to be bound to heterogeneous mRNA sequences and not to the 3' poly(A) tract. Crosslinking studies demonstrate that all of the pp56/60 present makes direct contact with the RNA. In vitro binding studies confirm that pp56/60 interact with single-stranded RNA of heterogeneous sequence, such as occurring in the maternal mRNA encoding cyclin B1. However, binding is equally effective to capped and polyadenylated cyclin mRNA, to truncated mRNA lacking 5' and 3' non-coding regions and even to the antisense sequence. Lengths of 70-80 nucleotides are protected from ribonuclease digestion after protein binding. Although no extended binding motif could be detected, binding does appear to have some specificity in that it is not competed out by 100-fold excess of double-stranded RNA, transfer RNA, poly(A) and various other homopolymers and heteropolymers. The sequence which competes most efficiently is the mixed polypyrimidine, poly(C,U). Crosslinking of RNA-protein complexes, followed by ribonuclease digestion, suggests that the arrangement of proteins on RNA is as dimers. Dimerization appears to be stabilized by phosphorylation of pp56/60. These results are discussed in terms of the known structures of pp56/60.

Animals↗