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Biomedical subjects

M M Gottesman

Publications and source records attributed to M M Gottesman.

At least 307 records · Page 17Linked to original sources
PubMed1980

Ultrastructural localization to 10 nm filaments of an insoluble 58K protein in cultured fibroblasts.

Using a simple procedure, we have isolated a Triton X-100 insoluble protein (58,000 mol wt) from cultured Chinese hamster ovary (CHO) cells, a fibroblastic cell line. The isolated protein, judged homogeneous by two-dimensional gel electrophoresis, was used to elicit antibodies in rabbits. The antiserum obtained is specific for the 58K protein as determined by immunoprecipitation from detergent solubilized 35S-labeled CHO cells and by antibody labeling of SDS solubilized Swiss 3T3 cell extracts separated on a 10% polyacrylamide gel. Indirect immunofluorescence localization with this antiserum in fixed permeabilized Swiss 3T3 cells, whose flat morphology makes them superior for localization studies, reveals filaments that radiate from the perinuclear region to the cell periphery. These filaments were identified as 10 nm filaments by electron microscopic localization using the EGS and ferritin bridge procedures. We conclude that the 58K protein is a major constituent of fibroblast 10 nm filaments. Other intracellular structures were not labeled by this technique.

Animals↗
PubMed1979

High frequency of mutation to tubercidin resistance in CHO cells.

The acquisition of high-level resistance to tubercidin (an adenosine analog) in CHO cells occurs in a single step at high frequency (10(-3) to 10(-4)) without mutagenesis. Analysis of a large number of independent mutants by a fluctuation test (Luria and Delbruk, 1943) indicates that they arise independently of the selection medium and all fall into the same complementation group. All mutants tested lack detectable adenosine kinase activity. An analysis of hybrids between mutant and wild-type cells indicates that resistance to tubercidin is a recessive marker which segregates as would be expected if it were a haploid locus in the parental CHO cell. Resistance to tubercidin is not linked to the X chromosome in CHO cells and appears to occur at much lower frequency in primary Chinese hamster cells and other cultured cell lines.

Animals↗
PubMed1978

The determination of similarities in amino acid composition among proteins separated by two-dimensional gel electrophoresis.

A simple and rapid procedure has been developed to determine similarities in amino acid composition among cellular proteins separated by two-dimensional gel electrophoresis. Cells in tissue culture are simultaneously labeled with two different amino acids each tagged with a different radioisotope. The proteins are then separated on two-dimensional gels and their location on the gels determined by Coomassie-blue staining or autoradiography. Elution of the protein from the appropriate region of the gel followed by liquid scintillation counting yields an isotope ratio which reflects the ratio of the two amino acids in the protein. Examples of the use of this technique in analyzing mutant proteins, proteins altered by carbamylation, and cell proteins with similar amino acid composition (e.g., actin and tubulin) are given.

Amino Acids↗
PubMed1978

Transformation-dependent secretion of a low molecular weight protein by murine fibroblasts.

A protocol has been devised to radiolabel proteins secreted by murine fibroblasts in vitro. A radiolabeled polypeptide of molecular weight 35,000 is released into medium in relatively large amounts by transformed cells and in much smaller amounts by nontransformed fibroblasts. This major excreted polypeptide (MEP) is found in the medium of spontaneously transformed mouse cells and in the medium of mouse cells transformed by a DNA tumor virus, RNA tumor viruses, or methylcholanthrene. The appearance of MEP appears to be well correlated with anchorage independence in these transformed cells. MEP can be localized within the cytoplasm of transformed but not untransformed cells by indirect immunofluorescence. The presence of MEP within murine fibroblasts or in their culture medium serves as a novel biochemical marker of transformation. A biological role for this protein has not been assigned.

Cell Line↗
PubMed1975

Acquisition of a determinant for chloramphenicol resistance by coliphage lambda.

A determinanat for chloramphenicol resistance, cam, initially detected on a resistance transfer factor (RTF) and since transferred to phage P1, may be acquired from P1 by coliphage lambda. Lambdapcam are obtained when a lambda prophage is induced in bacteria which also harbor P1 cam prophage. Lambdacam formation is not dependent upon host Rec or lambda Red recombination functions. Electron microscopic heteroduplex analysis shows that the cam locus in two lambdapcams is a 5% addition of DNA in the b2 region of lambda, not contiguous with att. The extent and nucloetide sequence of the DNA insertion in the two independent lambdapcam isolates appear to be the same though they are located at different sites within the b2 region. We conclude that the determinant for chloramphenicol resistance is contained on a unique piece of DNA which facilitates its insertion into a number of unrelated genomes.

Chloramphenicol↗