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D S Singer

Publications and source records attributed to D S Singer.

77 records · Page 5Linked to original sources
PubMed1982

Characterization of a porcine genomic clone encoding a major histocompatibility antigen: expression in mouse L cells.

A porcine genomic clone encoding a major histocompatibility, (MHC) antigen was isolated by direct screening of a swine genomic library with a heterologous human MHC cDNA probe. Mouse L cells transformed with DNA from the clone stably express swine MHC antigen. Pig alloantisera specifically lyse transformant but not control cell lines in a complement-mediated cytotoxicity assay. Direct immunoprecipitation of radiolabeled cellular protein from transformed lines by pig alloantiserum results in the coprecipitation of swine MHC heavy chain and mouse beta 2-microglobulin, demonstrating the association of heterologous subunits of MHC antigens.

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PubMed1979

Arrangement of a highly repeated DNA sequence in the genome and chromatin of the African green monkey.

The DNA of the African green monkey contains three components that are distinguishable by the kinetics of reassociation. The rapidly reassociating component represents about 20% of the total DNA and is composed almost entirely of a sequence (AGMr(HindIII)-1) which is repeated 6.8 x 10(6) times. The majority of the AGMr(HindIII)-1 sequences are organized in long tandem repeats of a segment of 172 base pairs in length. However, a fraction of the AGMr (HindIII)-1 sequences is interspersed with another 37% of the genome. The structure of the chromatin containing the AGMr-(HindIII)-1 sequence is indistinguishable from that containing total DNA. Furthermore, there is nothing inherent in the nucleotide sequence of AGMr(HindIII)-1 which specifies a unique location for nucleosomes.

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PubMed1976

H5 Histone and DNA-relaxing enzyme of chicken erythrocytes. Interaction with superhelical DNA.

The interaction of closed circular duplex DNA with the lysine-rich H5 histone fraction of avian erythrocytes has been studied. H5, like H1 histone, interacts preferentially with superhelical DNA. The extent of interaction increases with increasing negative or positive superhelicity. Salt-extracted lysine-rich histones show the same specificity for interaction with superhelices as do acid-extracted preparations. Chicken erythrocyte nuclei contain DNA-relaxing enzyme. This enzyme is extracted from the nuclei at lower salt concentrations than those required to extract H1 and H5 histones and is, therefore, probably a function of a protein distinct from H1 and H5 histones.

Animals↗
PubMed1976

Studies on the interaction of H1 histone with superhelical DNA: characterization of the recognition and binding regions of H1 histones.

The very lysine rich histone, H1, isolated from a variety of sources interacts preferentially with superhelical DNA compared to relaxed DNA duplexes. The nature of this specific interaction has been investigated by studying the ability of various purified fragments of H1 histone from calf thymus to recognize and bind superhelical DNA. The data suggest that the globular region of the H1 histone molecule (amino acid residues 72-106) is involved in the recognition of superhelical DNA. Thus, the H1 histone carboxy-terminal fragment, 72-212, resembles native H1 histone both quantitatively and qualitatively in its ability to discriminate between and bind to superhelical and relaxed DNA while the H1 histone carboxy-terminal fragment, residues 106-212, has lost this specificity, binding superhelical and relaxed DNA equally well. Furthermore, under conditions in which the globular region of the intact H1 histone has been unfolded, the molecule loses its ability to discriminate between superhelical and relaxed DNA, and binds both forms of DNA equally.

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