Search PubMed⌕ Search

Biomedical subjects

J Greenblatt

Publications and source records attributed to J Greenblatt.

99 records · Page 6Linked to original sources
PubMed1973

Regulation of the expression of the N gene of bacteriophage lambda.

A quantitative assay for the N protein of bacteriophage lambda has been used to study the in vivo regulation of N gene expression. The assay makes use of the observation that in a cell-free protein-synthesizing system from Escherichia coli programmed with lambdaN(-) DNA the lambda endolysin is made only if N protein is added to the reaction. The rate of synthesis of N protein in vivo is negatively controlled by the products of the CI and tof genes of the phage. Furthermore, N protein activity is extremely unstable in vivo. During normal cell growth at 35 degrees , the half-life of N protein is about 2 min.

Cell-Free System↗
PubMed1972

Positive control of endolysin synthesis in vitro by the gene N protein of phage lambda.

Positive control in vitro by gene N protein of bacteriophage lambda was demonstrated. lambda DNA was used to direct in vitro synthesis of lambda endolysin in a cell-free protein-synthesizing preparation derived from Escherichia coli. The endolysin synthesis depends on the concomitant in vitro synthesis of lambda gene N protein. When lambda N(-) DNA was used to direct the cell-free preparation, endolysin was made only if extract was added from cells in which a lambda prophage had been induced. The use of various prophage deletion strains proved that if this stimulating activity made in vivo is coded by a known lambda gene, it must be coded by gene N. The ability to stimulate endolysin synthesis in vitro on a lambda N(-) DNA template, therefore, constitutes an assay for N protein.

Chloramphenicol↗
PubMed1971

Relationships between relative binding affinity and electrophoretic behavior of rabbit antibodies to streptococcal carbohydrates.

After repeated intravenous injections with Group C streptococcal vaccine, most rabbit antisera were shown to contain one or more IgG antibody components, as revealed by microzone electrophoresis. A procedure for the fractionation of multiple IgG antibody components from such streptococcal antisera is described. Separation is achieved on the basis of differences in relative binding affinities of the antibody components to immunoabsorbent columns. The evidence suggests that the electrophoretic mobility, and thus the net charge of an antibody, bears a reciprocal relationship to its binding affinity for the streptococcal Group C antigens. Furthermore, the relative binding affinity affords another means to assess the functional homogeneity of streptococcal antibodies. A possible relationship between light chain variable-region subclasses and binding affinities of streptococcal antibodies is discussed.

Adsorption↗
PubMed1966

Myoglobinuria and skeletal muscle phosphorylase deficiency: report of a case of McArdle's disease.

Investigation of a patient complaining of exercise-induced dark urine, pain, stiffness and tenderness of skeletal muscle revealed findings characteristic of McArdle's disease. The dark urine was attributable to the excretion of myoglobin, and an ischemic exercise test failed to demonstrate the usual rise and fall in blood lactate and pyruvate. Enzyme assays of skeletal muscle showed an absence of phosphorylase, a slight increase in phosphorylase b kinase and a slight decrease in phosphoglucomutase. Chemical and histochemical analyses demonstrated an increase in the skeletal muscle glycogen content and an enlargement of the muscle cells. No abnormality of liver glycogen metabolism was found. In the absence of specific therapy, an effective and practical form of treatment is reduction of exercise below the threshold of symptoms.

Adult↗
PubMedDate not supplied

Antitermination of transcription by the N-gene protein of bacteriophage lambda: recent progress and remaining problems.

The N-gene protein of bacteriophage lambda recognizes sequences called nut in the lambda early operons and acts to prevent termination of the transcription of these operons. Part of the mechanism of action of N protein involves binding to the nusA protein of Escherichia coli, a transcription termination factor which associates directly with RNA polymerase. It is likely that N protein forms a ternary complex with the nusA protein and RNA polymerase at the nut site. Evidence is presented that translating ribosomes are not involved in N-protein action. It is still not known how RNA polymerase is modified to become termination-resistent as a result of N protein action.

Bacteriophage lambda↗