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M M Zakin

Publications and source records attributed to M M Zakin.

At least 73 records · Page 4Linked to original sources
PubMed1987

Molecular structure and early events in the replication of Tacaribe arenavirus S RNA.

Tacaribe arenavirus S RNA was cloned and analysis of its nucleotide sequence revealed two open reading frames of significant size, one in the virus-sense strand, the other in the virus-complementary strand. The predicted amino acid sequences of the two reading frames were compared with the predicted primary structures of the nucleoprotein (N) and glycoprotein precursor (GPC) of LCM, Pichinde and Lassa viruses. The results indicated a high degree of homology between the proteins of similar properties. It was also found that in Tacaribe virus-infected cells a subgenomic viral-sense GPC RNA and a subgenomic viral-complementary N RNA are synthesized in addition to the full length viral (v) RNA and viral complementary (vc) RNAs. These results support the conclusion that in Tacaribe virus--as in Pichinde and lymphocytic choriomeningitis arenavirus-S RNA encodes the viral N and GPC proteins and has an 'ambisense' coding strategy. Analysis of the S-derived RNA species at early times post-infection in cells incubated with or without inhibitors of protein synthesis indicated that for primary transcription of the N mRNA, protein synthesis is not required; whereas synthesis of the vc RNA, GPC mRNA and v RNA does require protein synthesis to take place.

Amino Acid Sequence↗
PubMed1987

Complete structure of the human transferrin gene. Comparison with analogous chicken gene and human pseudogene.

The complete structure of the human transferrin gene is presented. This gene has a total size of about 33.5 kb and is organized in 17 exons separated by 16 introns. The chicken ovotransferrin gene has a size of 10.5 kb and is also organized in 17 exons and 16 introns. The analysis of the structure of the two genes confirm, at the gene level, that transferrins originated by a gene duplication phenomenon. Finally, the existence of a new member of the transferrin family, a human transferrin non-processed pseudogene is demonstrated.

Amino Acid Sequence↗
PubMed1985

Organization of the human transferrin gene: direct evidence that it originated by gene duplication.

We present the characterization of two overlapping human transferrin genomic clones isolated from a liver DNA library. The two clones represent a total length of 24 kilobase pairs and code for 70% of the protein. The organization of this gene region was elucidated by restriction mapping and DNA sequencing. It contains 12 exons, ranging from 33 to 181 base pairs, separated by introns of 0.7-4.9 kilobase pairs. This gene can be divided into two unequal parts corresponding to the known domains of the protein. Each part is essentially composed of an equal number of exons; introns interrupt the coding sequences, creating homologous exons of similar size in each moiety. Moreover, the pattern of intron interruption of the codon sequence is identical for all the analyzed homologous exon pairs. Comparison with the organization of the ovotransferrin gene shows an identical exon size distribution. These data confirm, at the gene level, the hypothesis that transferrins originated by a gene-duplication event. A model accounting for the origin of the human transferrin gene is presented.

Amino Acid Sequence↗
PubMed1985

Modified oligonucleotides as alternatives to the synthesis of mixed probes for the screening of cDNA libraries.

Two simple alternatives to the synthesis of mixed oligodeoxyribonucleotide probes are described: mixed deblocking of triazolodeoxynucleosides for the A/G and C/T degeneracies or incorporation of 2-amino-2'-deoxyadenosines into a determined sequence for a higher stability of the hybridization duplexes. The synthetic oligodeoxyribonucleotides obtained were successfully tested in comparison with a classical mixed probe for their capacity to identify specific cDNA clones of human antithrombin III. The results are discussed with respect to the utilization of these synthetic oligonucleotides as hybridization probes for the isolation of cloned cDNA sequences.

Antithrombin III↗
PubMed1984

Structure and autoregulation of the metJ regulatory gene in Escherichia coli.

The nucleotide sequence of the Escherichia coli metJ regulatory gene (312 nucleotides) has been determined as well as that of two mutations located within the gene. Analysis of the sequence downstream from the metJ gene has revealed inverted repeats homologous to several intercistronic regions, also reported to occur between operons. A hybrid protein that contains the 55 first amino acid residues of the metJ protein substituting for the 8 amino acid residues at the NH2 terminus of beta-galactosidase was produced by gene fusion. The hybrid protein retaining beta-galactosidase activity was purified. Its amino-terminal sequence was determined and this allowed us to locate the translational start codon of the metJ gene. Evidence was provided for autoregulation by repression of the metJ gene. By sequencing upstream from metJ, the region situated between the metJ and metB genes was found to contain putative operator structures that we propose to call "Met boxes."

Alleles↗
PubMed1984

Molecular cloning and sequence analysis of cDNA for human transferrin.

A cDNA clone for human transferrin was identified from a human liver cDNA library by pre-screening with different ss-cDNA probes against length-fractionated liver mRNAs, positive hybridization-selection and nucleotide sequence analysis. The insert was of 1 kb, encoding human transferrin from aminoacid 403 through the COOH terminus, with a 3' non coding region of 166 nucleotides. This insert hybridized with a single major mRNA species of about 2.4 kb and several genomic DNA restriction fragments. Hybridization of the Southern blots with different parts of the transferrin insert and at different stringences suggest that the various bands observed correspond to splice sites inside one gene rather than to hybridization to several related genes. Finally, a single or a low number of transferrin gene copies seem to exist in the human genome.

Animals↗
PubMed1984

Internal homologies in the two aspartokinase-homoserine dehydrogenases of Escherichia coli K-12.

In Escherichia coli, AK I- HDH I and AK II- HDH II are two bifunctional proteins, derived from a common ancestor, that catalyze the first and third reactions of the common pathway leading to threonine and methionine. An extensive amino acid sequence comparison of both molecules reveals two main features on each of them: (i) two segments, each of about 130 amino acids, covering the first one-third of the polypeptide chain, are similar to each other and (ii) two segments, each of about 250 amino acids and covering the COOH-terminal 500 amino acids also present a significant homology. These findings suggest that these two regions may have evolved independently of each other by a process of gene duplication and fusion previous to the appearance of an ancestral aspartokinase-homoserine dehydrogenase molecule.

Amino Acid Sequence↗
PubMed1983

Structure of the metJBLF cluster in Escherichia coli K12. Sequence of the metB structural gene and of the 5'- and 3'-flanking regions of the metBL operon.

The total nucleotide sequence (1,158 nucleotides) of the metB gene of Escherichia coli coding for cystathionine gamma-synthase (386 amino acid residues, Mr = 41,503/chain) is presented. The nucleotide sequences of the flanking regions of the metB and metL genes are also presented. Analysis of these sequences and identification of a promoter region upstream from the metB gene confirms that metB and metL form an operon. The transcription direction is from metB to metL; the start site of the gene transcription has been determined. There is no structural evidence of a classical attenuation mechanism in the regulation of this operon coding for enzymes implicated in an amino acid biosynthetic pathway. Finally, the overall organization of the metJBLF gene cluster is discussed.

Amino Acid Sequence↗
PubMed1983

Nucleotide sequence of a cDNA clone for human aldolase B.

Two specific clones for human aldolase B were isolated from a human liver cDNA library using a rat aldolase B cDNA probe. The clones were identified by positive hybridization-selection and one of them was sequenced. The 127 C-terminal residues of the human protein were deduced from this nucleotide sequence analysis. They showed 92% homology with the corresponding previously published amino-acid sequence of rat liver aldolase B.

Amino Acid Sequence↗
PubMed1983

Nucleotide sequence of metF, the E. coli structural gene for 5-10 methylene tetrahydrofolate reductase and of its control region.

The nucleotide sequence of the E.coli metF gene (888 nucleotides), coding for 5-10 methylene tetrahydrofolate reductase, has been determined. The metF gene product was identified in maxicells and found to be a protein of subunit molecular weight 33,000, in agreement with the size of the coding region. The starting point for metF transcription was determined by S1 nuclease mapping. No structural evidence was found for an attenuation mechanism regulating the independent metF transcriptional unit. Comparison of the regulatory region preceding the metF structural gene with the 5' flanking region of the metBL operon shows some homology spanning 24 nucleotides. These homologous sequences could be operator structures belonging to the two transcriptional units, metF and metBL, and recognized by the same regulatory protein.

5,10-Methylenetetrahydrofolate Reductase (FADH2)↗
PubMed1982

Construction and physical mapping of plasmids containing the metJBLF gene cluster of E. coli K12.

In vitro recombination techniques were used to clone the E. coli metJBLF gene cluster in a plasmid vector. Several chimeric plasmids were obtained, analyzed by restriction mapping and characterized genetically. The combined results establish that the met gene cluster is contained on an approximately 5.6 kilobase segment of bacterial DNA with metL between metB and metF. The origin of metL was localized precisely by its DNA sequence and its transcription direction was established.

Bacteriophage lambda↗