PubMed Health⌕ Search

Biomedical subjects

N Spoerel

Publications and source records attributed to N Spoerel.

9 recordsLinked to original sources
PubMed1997

TPO1, a member of a novel protein family, is developmentally regulated in cultured oligodendrocytes.

Although the myelin membrane contains only a small set of major proteins, more sensitive assays indicate the presence of a plethora of uncharacterized proteins. We have used an antibody perturbation approach to reversibly block the differentiation of prooligodendroblasts into myelinating cells, and, in combination with a differential screening procedure, identified novel mRNAs that are activated during this period. One cDNA, TPO1, recognizes a 5.5-kb mRNA that is strongly up-regulated in oligodendrocytes after release of the differentiation block and that is expressed at high levels in brain tissue during active myelination. This cDNA represents at least two mRNAs differing from each other in their 5'-termini. The TPO1 cDNA contains an open reading frame of 1,380 bp, encoding a protein of 51.8 kDa with a predicted pI of 9.1 that contains two regions homologous to nonclassic zinc finger motifs. Subcellular localization studies suggest the enriched presence of TPO1 in spherical structures along the major cytoplasmic processes of oligodendrocytes. TPO1, along with homologues expressed in testis, placenta, and PC12 cells, form a novel family of proteins with multiple hydrophobic domains possibly serving as membrane spanning regions. We postulate that in oligodendrocytes, TPO1 encodes a protein factor involved in myelin biogenesis.

Amino Acid Sequence↗
PubMed1987

A short 5'-flanking DNA region is sufficient for developmentally correct expression of moth chorion genes in Drosophila.

Fusions with the bacterial gene for chloramphenicol acetyltransferase followed by P-element-mediated germ-line transformation in Drosophila have permitted localization of the DNA sequence that confers a high degree of developmental specificity on a pair of silkmoth eggshell (chorion) genes. The short, 272-base-pair, 5'-flanking region shared by the divergently transcribed genes is sufficient for developmentally appropriate expression when placed upstream of the chloramphenicol acetyltransferase gene, in either orientation. A highly conserved motif within that region, TCACGT, is essential for chorion-specific expression.

Animals↗
PubMed1986

Gene regulation and evolution in the chorion locus of Bombyx mori. Structural and developmental characterization of four eggshell genes and their flanking DNA regions.

We report on the detailed structural and developmental characterization of four chorion genes and a truncated pseudogene located within a 9.5 X 10(3) base chromosomal segment. These genes belong to the A and B multigene families and, like previously characterized moth chorion genes, are arranged in tightly linked pairs, which are divergently transcribed (A/B.L11 and A/B.L12). On the basis of their high degree of sequence divergence, the A genes define two distinct subfamilies, while the more homologous B genes represent different copies of the same gene type. The A.L11 and B.L11 introns are much longer, in each case because of a single inserted DNA segment that is missing from A.L12 or B.L12. The 2.1 X 10(3) base insertion in A.L11 is the first retrovirus-like transposable element characterized in Bombyx mori. The very short 5' flanking sequences of A/B.L11 and A/B.L12 (277 and 276 base-pairs) are distinct as shown by hybridization but both recur in additional chorion gene pairs, forming two respective classes that are expressed during distinctly different developmental periods. The divergently transcribed genes of each pair, which border the same 5' flanking sequence, are expressed co-ordinately, during the same developmental period. Detailed comparisons of the 5' flanking regions, and of the corresponding region of the Drosophila s15-1 chorion gene, revealed numerous, very short sequence elements that are shared. One such element, T-C-A-C-G-T, is also associated with all five sequenced Drosophila chorion genes. Some elements are repeated in a dyad symmetrical pattern, i.e. are associated with each of the two genes in a pair, while others, including T-C-A-C-G-T, occur only once per 5' flanking region, and, if functionally important, would presumably act bi-directionally on both genes of the pair.

Animals↗
PubMed1985

Coding and potential regulatory sequences of a cluster of chorion genes in Drosophila melanogaster.

We have characterized at the nucleotide level a 4.8-kilobase pair segment of the third chromosome of Drosophila melanogaster, which contains a cluster of three chorion genes, s18-1, s15-1 and s19-1. These genes are tandemly oriented and share the same basic organization: a small and a large exon separated by a short intron in the signal peptide region. In the coding region, limited similarities at the DNA and protein level suggest a common but distant evolutionary origin. The flanking sequences were searched for elements that might be involved in controlling the tissue-specific and temporally regulated expression and the selective amplification of the chorion genes. A good candidate for a cis-regulatory element is the hexamer, TCACGT, which is found in all three genes in a highly significant position, 23 to 27 nucleotides upstream of the TATA-box, accompanied by additional, less exact similarities. Palindromes and short inverted repeats that are found in the vicinity of their complement are non-uniformly distributed: they are most concentrated in the 3' flanking part of all three genes, in and near regions of unusually high A and T content. The highest number of dyad symmetries, reminiscent of sequences that function as viral replication origins, is found associated with the T- and A-rich regions between genes s18-1 and s15-1.

Amino Acid Sequence↗
PubMed1983

The messenger RNA for alcohol dehydrogenase in Drosophila melanogaster differs in its 5' end in different developmental stages.

Alcohol dehydrogenase (EC 1.1.1.1) of Drosophila melanogaster is coded by a single structural gene, active in both larvae and adults. The major larval and adult transcripts of Adh differ in their 5'-untranslated regions. The major larval mRNA is about 1100 bases long, some 50 bases shorter than the major adult transcript. The 5' end of the larval mRNA is colinear with the genomic sequence immediately adjacent to the coding region, starting 70 base pairs (bp) upstream of the initiation codon. By contrast, the adult mRNA shares only 36 of its 123 5'-untranslated bases with the larval mRNA; the remaining 87 are encoded by a sequence 654 bp upstream. Both initiation sites are preceded by a TATA box some 24 bp upstream. The developmental specificity of Adh expression is seen, therefore, to have a counterpart in the specificity of transcription initiation at the two separate promoter regions.

Alcohol Dehydrogenase↗
PubMed1979

Colivirus-T3-coded S-adenosylmethionine hydrolase.

Bacteriophage T3 induces an enzyme activity which hydrolyzes S-adenosylmethionine. This S-adenosylmethionine hydrolase is interesting, not only because of its unique activity, but also because the protein has to overcome host restriction [F. W. Studier and N. R. Movva (1976) J. Virol. 19, 136-145]. S-Adenosylmethionine hydrolase was purified to homogeneity using affinity chromatography on S-adenosylhomocysteine-Sepharose. The enzyme occurs in two forms, A and B. Form A consists of the viral peptide chain only; its native and subunit molecular weight is 17,000. Form B contains, in addition, a host subunit with a molecular weight of 49,000. The host subunit does not modify S-adenosylmethionine cleavage in vitro and no apparent relationship to the host-restriction system could be detected.

Bacterial Proteins↗
PubMed1979

A novel bacteriophage defence mechanism: the anti-restriction protein.

Bacteriophage T3 and T7 protect their DNA from restriction by producing, as the earliest detectable phage functions, anti-restriction proteins. Although the two phage proteins differ in their chromatographic and antigenic properties, they act by the same mechanism: the anti-restriction proteins inhibit E. coli K12 restriction endonuclease by direct interaction.

Coliphages↗