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Biomedical subjects

M D Scharff

Publications and source records attributed to M D Scharff.

At least 145 records · Page 8Linked to original sources
PubMed1975

Variants of a mouse myeloma cell line that synthesize immunoglobulin heavy chains having an altered serotype.

Cells of the MPC-11 mouse myeloma cell line, which produces an IgG2b immunoglobulin, were subjected to mutagenesis with Melphalan or with ICR-191, after which they were cloned in soft agar. Approximately 0.5 percent of the clones produced altered heavy chains that: (i) were the same size as or larger than the parent; (ii) no longer recognized by antibody specific for the parent gamma2b subclass; (iv) were recognized by antibody against the Fab (NH2-terminal half) of the parental immunoglobulin, but lacked some of the antigenic determinants of the Fc (COOH-terminal half) of the heavy chain; (v) lacked many of the tryptic/chymotryptic peptides found in the parent; (vi) contained tryptic/chymotryptic peptides that were not present in the parent but were present in an unrelated gamma2a myeloma heavy chain; and (vii) assembled with light chains by a pathway typical of IgG2a myelomas.

Amino Acid Sequence↗
PubMed1975

Heavy chain-producing variants of a mouse myeloma cell line.

Eleven variants producing only heavy (H) chains have been isolated from the P3 cell line after mutagenesis with either ICR-191 or nitrosoguanidine. The H chains produced by these variants are similar both in molecular weight and by peptide maps with the parental H chain. H chains dimerize intreacellularly, are not secreted but persist as stable cytoplasmic proteins. No evidence for the continued synthesis of light (L) chains of L chain fragments has been found in these variants. These studies show that, in the P3 cell line, the synthesis of H chains can continue in the absence of detectable L chain synthesis.

Acridines↗
PubMed1974

Independent synthesis of light and heavy chains: quantitation of light-chain production by mouse myeloma variants.

The rates of immunoglobulin synthesis have been examined in two MFC-11 cell lines which were independently adapted to tissue culture and in light-chain-producing variants derived from each of them. One cell line synthesized 2.5 pg immunoglobulin/cell/h, while the other synthesized 3.6 pg immunoglobulin/cell/h. The ratio of heavy and light chains in the two cell lines was approximately the same, and the size of the intracellular pool of immunoglobulin was proportioned to the rate of synthesis. Variants which had spontaneously lost the ability to produce heavy chains continued to synthesize light chains at approximately the same rate as their parent cell line.

Animals↗
PubMed1974

Variants of mouse myeloma cells that produce short immunoglobulin heavy chains.

After mutagenesis of cultured mouse myeloma cells with ICR 191 or Melphalan, variant clones were isolated that synthesized immunoglobulin heavy chains shorter than those produced by the parent. These variants fell into two phenotypes, based on the size, serology, and pattern of assembly of the heavy chain. Variant chains of both types no longer reacted with antisera directed either against the Fc (C-terminal half of the heavy chains) or subclass-specific IgG(2b) determinants. Comparative ion exchange chromatography of tryptic-chymotryptic peptides confirmed that the variant heavy chains differed structurally from those of the parent and from each other. A conversion from one phenotype to the other has been observed.

Acridines↗
PubMed1973

Mutations in immunoglobulin-producing mouse myeloma cells.

Three mouse myeloma cell lines were cloned in soft agar and screened by an antiserum overlay method for variants defective in secretion of the myeloma protein. Variants that had lost the capacity to synthesize heavy chains arose spontaneously at a high rate of about 10(-3) per cell per generation. Such variants lost the capacity to produce light chains at a similarly high rate. After cells were treated with the acridine half mustard ICR-191, variants occurred with an even higher incidence, and some of these synthesized heavy chains differing from that of the parent.

Acridines↗
PubMed1973

The synthesis, assembly, and secretion of gamma globulin by mouse myeloma cells. VI. Assembly of IgM proteins.

The study of the synthesis, assembly, and secretion of IgM by seven murine myeloma tumors has revealed that free mu chain can be detected intracellularly after release from the ribosome. It combines with light chains to form microL. The major intracellular protein in six of the seven tumors was the 8S subunit. One tumor contained considerable amounts of 19S material intracellularly. Those tumors that did not contain 19S IgM intracellulariy appeared to assemble the subunits outside the cell.

Animals↗