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Biomedical subjects

B Koller

Publications and source records attributed to B Koller.

48 records · Page 3Linked to original sources
PubMed1983

Preliminary structural characterization of the leukocyte cell surface molecule recognized by monoclonal antibody TA-1.

TA-1 is a monoclonal antibody identifying a cell surface molecule with a broad distribution on normal and malignant human leukocytes. Preliminary structural studies performed by using radioimmunoprecipitation and sodium dodecyl sulfate polyacrylamide gel electrophoresis indicated that TA-1 recognizes a two-chain polypeptide of approximately 170 kilodaltons (KD) and 95 KD under reducing conditions. The same experiment conducted under nonreducing conditions yielded bands of approximately 155 KD and 110 KD, suggesting the existence of intrachain disulfide bonds in both subunits. Both polypeptide chains were labeled with tritiated sodium borohydride after treatment of cells with neuraminidase and galactose oxidase, thereby demonstrating that both were glycosylated. Tryptic peptide mapping indicated that the 170-KD and 95-KD subunits did not have significant homology in peptide composition. We are designating this newly defined human leukocyte bimolecular complex gp 170/95.

Antibodies, Monoclonal↗
PubMed1982

Origin of replication in chloroplast DNA of Euglena gracilis located close to the region of variable size.

Chloroplast DNA (cpDNA), containing 10% replicative molecules, was isolated 2 h after onset of the dark period from cultures of Euglena gracilis strain Z. The DNA was digested with the restriction enzymes PvuII, SalI, BamHI, or EcoRI. Fragments that contained intact replicative loops were measured to determine the position of replicated sequences in relation to the restriction enzyme sites. It was found that replication starts at a unique position near one of the palindromic sequences I(2) (Koller and Delius, 1982a) which is located upstream (with respect to the direction of rRNA transcription) of the AT-rich region of variable size (Jenni et al., 1981; Schlunegger et al., in preparation). In the majority of cases DNA synthesis proceeds unidirectionally away from this region for 5000 nucleotides before it starts in the other direction (in the same sense as the rRNA transcription) through the Z-region and the second palindromic sequence.

Journal Article↗
PubMed1982

The organization of the chloroplast DNA in wheat and maize in the region containing the LS gene.

The DNAs of the plasmids pTac39 and pZmB1B, which contain the wheat chloroplast DNA BamHI fragment 2 and the maize chloroplast DNA BamHI fragment 9 respectively, were analysed by electron microscopy and by Northern blotting. Both plasmids contain the gene for the large subunit of ribulose bisphosphate carboxylase (LS gene). Comparison of the DNAs of the two species by partial denaturation and heteroduplex analysis shows extended homologies interspersed with a fine pattern of non-homology. On analysis of wheat-RNA X maize-DNA hybrids a region of non-homology at the 3' end of the LS mRNA of about 200 bases was found. Analysis of wheat DNA X RNA hybrids showed that the wheat LS mRNA contains 1700 +/- 50 bases and another hybrid, containing 2400 bases was also shown to occur in a position adjacent to that formed by the LS mRNA. Binding of Escherichia coli RNA polymerase and the start of transcription in vitro occurred at well-defined sites, which are located between or close to the positions where mRNA X DNA hybrids are found. A modified technique for the preparation and fractionation by electrophoresis of glyoxalated RNA is described.

Carboxy-Lyases↗
PubMed1981

Allo-responsive T lymphocytes and their differentiation markers.

Functionally disparate subpopulations of T lymphocytes that respond to alloantigens, primarily as studied in vitro in the mixed leukocyte culture and cell mediated lympholysis assays, have been separated most usefully by cell surface markers that can be identified with antiserums. Based on the data available to date there are at least two, and perhaps three, T lymphocyte subpopulations responsive to alloantigens in vitro, which include helper, cytotoxic, and perhaps suppressor T lymphocytes. Reviewed in this paper are data pertaining to the question of whether two types of cytotoxic T lymphocytes exist and whether true memory cytotoxic T lymphocytes are generated following in vitro or in vivo priming. Further, two systems are discussed that served as differentiation markers on lymphocytes: the Ly antigens and a family of large cell surface membrane proteins (LMPs).

Animals↗
PubMed1980

Electron microscopic mapping and sequence analysis of the terminator for the early message of E. coli phage T7.

The terminator position of T7 early messenger RNA was determined by electron microscopic measurements. The end of the RNA was mapped at a position 18.9% from the left end of T7 DNA, and 145 +/- 25 nucleotides from the right end of the Hpa I fragment Q. The sequence of the Hpa I Q fragment was determined around this position, and a terminator-like structure was detected in position 193 to 169 from the right end of fragment Q.

Base Sequence↗
PubMed1980

Family of large surface proteins on human lymphocytes.

Cell surface molecules of T-rosette-positive human peripheral blood lymphocytes were labelled by lactoperoxidase and examined on 5% polyacrylamide gels. Several bands, ranging in molecular weight from 220,000 to 170,000 daltons, were seen. Analysis of the tryptic and chymotryptic digests of the 187K, 200K, 210K and 220K proteins indicated that they are of similar peptide composition. Study of clones derived from this population indicated that individual cells within a population differed in expression of these proteins.

Animals↗
PubMed1980

Molecular relationships between large membrane proteins (LMP) expressed on T and B lymphocytes.

Clones prepared from day 5 mixed lymphocyte cultures (MLC) were examined for the expression of large (170,000- to 200,000-dalton) membrane proteins (LMP), found on bulk cultures of resting and allogeneically activated T lymphocytes. Sodium dodecyl sulfate-poly-acrylamide gel electrophoresis (SDS-PAGE) of these proteins indicates both bulk populations and noncytotoxic clones express LMP of similar m.w. Peptide mapping further indicates that LMP of 187,000 (187K) and 200K daltons, found on T cells from bulk cultures or clones and the 220K dalton LMP from B cells, all appear to have a very similar peptide composition. This suggests a single protein (or series of closely related proteins) is differentially processed in functionally disparate populations, and hence may serve as a differentiation antigen for these populations.

Animals↗
PubMed1978

The isolation of DNA from agarose gels by electrophoretic elution onto malachite green-polyacrylamide columns.

Electrophoretic elution of DNA coupled with direct adsorption onto malachite green-polyacrylamide columns was used to isolate double- and single-stranded DNA from agarose gels. Subsequently, DNA was eluted with a high salt buffer and filtered through Sephadex which permitted recovery of the DNA in a low salt buffer at concentrations suitable for heteroduplex analysis by electron microscopy. This method was tested by examining heteroduplexes formed from the isolated complementary single strands of T7 wild type DNA and a T7 deletion mutant. More than 80% of the reannealed molecules were intact heteroduplexes showing the deletion loop. Irradiation of single-stranded DNA with 254 nm light resulted in distorted, convoluted heteroduplexes while 366 nm light did not show this effect.

Coliphages↗