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Z E Zehner

Publications and source records attributed to Z E Zehner.

30 records · Page 2Linked to original sources
PubMed1989

Flanking sequences are required for efficient transcription and stable complex formation for the human tRNAiMet3-coding gene.

An analysis of 5' and 3' deletions of the human tRNAiMet3 gene has revealed upstream regions required for efficient transcription and stable complex formation in vitro. The 5' boundary of this essential region lies between nucleotides -39 to -18 (start point = + 1), and it has been shown that 3'-flanking sequences near the first termination site are also important for stable complex formation. The transcriptional efficiency of two non-allelic loci (TMET3 and TMET2) has been compared and TMET2 is more active. An analysis of chimeric (hybrid) genes indicates that much of the difference seen is due to 5'-flanking sequences and that there may be complex interactions between 5' and 3' sequences.

Animals↗
PubMed1988

Multiple elements are required for expression of an intermediate filament gene.

The expression of vimentin is unique within the intermediate filament multigene family. It is the only member which deviates from its usual tissue-specific expression pattern and whose 5'-flanking region contains multiple GC boxes, the binding site for Sp1. The activity of vimentin 5'-end:CAT fusions has been compared in cells where vimentin is highly expressed (mouse L cells) or not expressed at all (MH1C1). In addition, CAT activity has been examined by microinjection into Xenopus oocytes. Both in vivo expression and in vitro binding studies implicate Sp1 as a general regulatory factor in vimentin gene expression. Increased expression of 5'-end:CAT fusions in mouse L cells suggests that a fibroblast-specific enhancer element resides in the region -321 to -160. Low transcriptional activity in MH1C1 cells may be due to either the lack of this positive transcription factor(s) or the presence of a repressor element. Here, we demonstrate that the unique and complex pattern of vimentin gene expression is controlled by multiple cis-acting elements.

Animals↗
PubMed1987

The chicken vimentin gene. Nucleotide sequence, regulatory elements, and comparison to the hamster gene.

Here we report the nucleotide sequence of the chicken vimentin gene and its deduced primary amino acid sequence. A comparison of this gene to other intermediate filament protein genes demonstrates that both exon size and position are strongly conserved features of this multigene family. In addition, the hamster and chicken vimentin genes exhibit strong identity at the level of nucleotide (74%) and amino acid (80%) sequence. Interestingly, 40% of total sequence diversity is localized to the N terminus or "head" region of these genes whereas other protein domains (rod and C terminus) are remarkably identical in both nucleotide (81%) and amino acid (89%) sequence. Even stronger amino acid identity (100%) is exhibited in certain subdomains which may define regions crucial for filament formation and function. Not surprisingly, vimentin is more homologous across animal species than it is to other intermediate filament protein members (e.g. desmin) within the same species. A comparison of 5'-flanking sequences of the hamster and chicken genes as well as other characterized promoter elements (SV40, HSV-TK) reveals homologous sequence elements which may define common and/or unique sites involved in the modulation of gene expression. The implications of these sequence elements for both tissue-specific and developmental expression of the vimentin gene are discussed.

Amino Acid Sequence↗
PubMed1987

A human tRNA(iMet) gene produces multiple transcripts.

A third nonallelic locus of the human methionyl-tRNA multigene family (tRNA(iMet-3) was isolated. This gene, unlike two other tRNA(iMet) loci, lacks a remarkable run of T and C residues which functions as a termination of transcription signal. Instead, three tandem termination signals, each containing no more than four thymidylate residues, function as relatively inefficient termination signals. As a result, polymerase readthrough generates at least three transcripts in vitro. The efficiency of apparent termination varies significantly at these sites. All resulting transcripts appear to be processed in vitro.

Base Sequence↗
PubMed1985

The chicken vimentin gene: aspects of organization and transcription during myogenesis.

The intermediate filament gene vimentin exists in a single copy in the chick haploid genome. However, it exhibits the curious property of producing at least three functional vimentin mRNA transcripts in vivo through the differential utilization of multiple polyadenylylation sites. According to one group in erythroid cells there may be a tissue-specific utilization of one of these poly A addition sites. The chicken and hamster vimentin genes exhibit remarkable nucleotide sequence homology both within coding and 3'-noncoding regions (82%). This nucleotide homology extends both to the size and juxtaposition of exons. With the noted exception of valine, even the frequency of codons utilized is strongly conserved across the widely different species. Of course, this strong homology at the DNA level extends to an amino acid homology of 92% between vimentins and 65% between related proteins in the same species.

Amino Acid Sequence↗
PubMed1983

Vimentin gene expression during myogenesis: two functional transcripts from a single copy gene.

We have previously reported that a single vimentin gene is present in the chicken genome (22). In vivo transcription of this gene yields two distinct classes of mRNA's (approximatley 2200 and-2500 nts) generated through the possible differential utilization of polyadenylylation sites. In this report we demonstrate that 1) both transcripts are functional in vitro and direct the cell-free synthesis of the vimentin polypeptide, as judged by two dimensional gel analysis; 2) three of the four possible adenylylation signals indicated in the sequence of the gene are utilized in vivo as determined by S1 analysis; 3) furthermore, these adenylylation sites are utilized identically in all tissues of the chicken examined; 4) the adenylylation site closest to the body of the message is apparently not used as judged by the S1 conditions employed in the assay. Levels of vimentin mRNA decrease in different tissues of the chicken during the embryonic to adult transition. There is no evidence for a tissue specific or developmentally regulated pattern of expression for either of the two vimentin transcripts. The same pattern of vimentin mRNA expression is seen in all tissues examined, only the level of expression is altered.

Aging↗
PubMed1983

Characterization of the chicken vimentin gene: single copy gene producing multiple mRNAs.

Genomic clones and cDNA plasmids were isolated for the intermediate filament protein vimentin from chicken. The identity of the various clones was determined both by mRNA selection [Paterson, B. M. & Roberts, B. E. (1981) in Gene Amplification and Analysis, Structural Analysis or Nucleic Acids, eds. Chirikjian, J. G. & Papas, T. S. (Elsevier, North Holland), Vol. 2, pp. 418-435] and nucleotide sequence analysis. Restriction analysis, hybridization data, and heteroduplex studies confirmed that all of the genomic isolates contained overlapping fragments of an identical vimentin gene. No evidence for the existence of a second vimentin gene could be found by a Southern analysis either by using coding fragments from the purified vimentin gene or by using cDNA plasmids as probe. Likewise, copy-number experiments verified that the vimentin gene was present only once in the haploid chicken genome. However, in a RNA blot analysis, at least two equally abundant vimentin mRNA species of approximately 2,200 and 2,500 nucleotides in length were detected in all RNAs tested. Sequence analysis revealed that the vimentin gene contained two sets of tandem polyadenylylation sites, 249 and 532 nucleotides downstream from the stop codon for protein synthesis. It is proposed that the larger mRNA species arise because of complete transcription of the 3'-end of the vimentin gene (560 nucleotides of 3' nontranslated sequence), whereas the smaller mRNA species terminate after the first set of polyadenylylation sites.

Animals↗
PubMed1980

Goose fatty acid synthetase mRNA.

The fatty acid synthetase of animal tissues consists of two identical subunits (Mr = 250,000), each of which is a multienzyme protein containing domains for the acyl carrier peptide and the seven different catalytic activities required for the conversion of acetyl-CoA and malonyl-CoA to palmitate. Total poly(A+) RNA was isolated from goose uropygial gland and translated in a cell-free rabbit reticulocyte system. The translation products contained a polypeptide having the same molecular weight as the native synthetase subunits; this protein was specifically recognized by anti-synthetase antibodies and could be competed by excess native synthetase for antibody binding. Fractionation of the poly(A+) RNA by sucrose gradient centrifugation showed that synthetase mRNA is very large, repeatedly exhibiting a sedimentation coefficient of 35 S. Gel electrophoresis of this purified mRNA fraction following glyoxylation showed the presence of several species of RNA, one of which correlated well with the in vitro translation of the synthetase. This mRNA species has a molecular weight of 2.95 X 10(6), which is large enough to code for a protein with a molecular weight of 250,000. These results confirm the multifunctional nature of the synthetase and indicate that the synthetase subunit must arise as a single polypeptide chain synthesized from one contiguous mRNA.

Animals↗
PubMed1975

Multiple thermotropic phase transitions in Escherichia coli membranes and membrane lipids. A comparison of results obtained by nitroxyl stearate paramagnetic resonance, pyrene excimer fluorescence, and enzyme activity measurements.

At characteristic temperatures, membranes from Escherichia coli cells enriched in exogenous elaidic acid exhibit two abrupt changes in the slope of Arrhenius plots of two enzyme activities. For NADH oxidase, these changes occur at 27 degrees and 32 degrees, whereas for D-lactate oxidase, these changes occur at 31 degrees and 36 degrees. Pyrene excimer fluorescence and spin-labeled fatty acid paramagnetic resonance results indicate that the beginning, midpoint, and end of a single structural change(order leads to disorder transition) occurs at 25.5-29.0 degrees, 30.0-31.0 degrees, and 33.0-35.5 degrees, respectively. These data suggest that for NADH oxidase, the observed activity changes correspond to the beginning and midpoint of a single membrane lipid structural change, whereas for D-lactate, the activity changes correspond to the midpoint and end of that structural change. In addition to the membrane structural change spanning the range of 25.5-35.5 degrees, a second change (9.5-21.0 degrees) was also observed. This transition was detected by 5- and 16-2,2-dimethyloxazolidinyl-1-oxyl (doxyl) stearates, but not by 12-doxyl stearate or pyrene. Structural changes in the extracted lipids were observed in the temperature ranges 4.0-9.0 degrees, 14.0-20.0 degrees, and 25.0-35.5 degrees. The two higher ranges correlate well with the ranges for structural changes observed in the intact membrane. Observations of these multiple transitions in both intact membranes and extracted lipids strongly suggest that these lipids segregate into domains of different fluidity and composition.

Cell Membrane↗