Independent Synthesis of Light and Heavy Chains

Laskov, Reuven; Scharff, Matthew D.

doi:10.1084/jem.140.4.1112

Cited by 19 publications

(3 citation statements)

References 22 publications

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“…We were unable to detect either secreted or intracellular K in these ,unonsecreting cell lines. This result contrasts with earlier studies in which mutants expressing K chain in the absence of heavy chain production were frequently obtained (1,2,9,30,32,37,52). Cell lines making only intracellular heavy chain and no light chain have been isolated as Abelson virus-induced tumors (46), fetal liver cell hybridomas (5), and as myeloma mutants (36,48).…”

Section: Resultscontrasting

confidence: 58%

Mutations Affecting the Structure and Function of Immunoglobulin M

Shulman

Heusser

Filkin

et al. 1982

Molecular and Cellular Biology

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Using a hybridoma cell line which secretes hapten-specific immunoglobulin M (IgM), we have isolated a variety of mutants which produce abnormal immunoglobulin. Immunoglobulin was tested for the size and composition of the component heavy and light chains and for variable and constant region related functional and serological activities. Some mutants secrete IgM which seems to be defective in hapten binding; others make IgM which appears not to activate complement. Many of the mutants secrete monomeric as opposed to pentameric IgM. In some cases, the defect apparently correlates with structural alterations in the mu heavy chain: partial deletion, polypeptide addition, and abnormal glycosylation have been observed. These mutant cell lines provide a means of identifying the structural basis of IgM function and of studying the biochemistry of IgM synthesis and processing.

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Section: Resultscontrasting

confidence: 58%

Mutations Affecting the Structure and Function of Immunoglobulin M

Shulman

Heusser

Filkin

et al. 1982

Molecular and Cellular Biology

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“…Since myeloma cells contain 17 pg/cell of polysoma1 RNA' and 2"/, of the polysomal RNA is poly(A)-containing mRNA [32], it can be calculated that the translatable x and y mRNA pool sizes are about 30 000 and 20 000 molecules/cell respectively. These pool size values can account for the absolute synthesis rate of (4-6)x lo' and (2-4)x 10' molecules min-' cell-' previously determined for the x and y polypeptide chains respectively [6]. This is so since the x and y polysomes were found to contain 6-8 and 16-18 ribosomes respectively [33], and the translation times of the respective mRNA molecules were approximately 0.5 min and 2.0 rnin [30], a pool size of 3 x lo4 )c polysomes will produce the il chain at a rate of about 4.2 x 10' molecules min-' cell-' (7 ribosomes x 3 x lo4 polysomes x 1/O.S min).…”

Section: Discussionmentioning

confidence: 99%

“…Previous studies have demonstrated that 16 -36 of the total proteins produced by murine myeloma cells is Ig [5,6]. Since plasmacytoma cells appear to contain just one copy per haploid genome of the constant part of the light [7,8] and heavy-chain genes [9], the amplified synthesis of IgG cannot be explained by gene amplification.…”

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confidence: 99%

A High Production Rate of Translatable IgG mRNA Accounts for the Amplified Synthesis of IgG in Myeloma Cells

Wallach

Laskov

1980

European Journal of Biochemistry

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The aim of the present work was to determine whether the accumulation of Ig mRNA in myeloma cells is due to a high rate of production or to a high stability of these molecules. Specific mRNAs for the light and heavy polypeptide chains of IgG were isolated from the murine MPC‐11 myeloma tumor cells by immune precipitation of polysomes which synthesize these chains. It was found that the immune‐precipitated polysomes were enriched 10 –30‐fold in the γ and χ mRNA sequences respectively. In the wheal germ cell‐free system the χ mRNA preparation was translated mainly into three polypeptides of Mr 25000, 18000, and 15000. The method of immune precipitation of polysomes was also used to characterize three variant clones of MPC‐11 myeloma. It was found that little if any γ‐chain polysomes are present in the L‐chain producer and non‐producer clones, while a substantial amount of χ‐chain polysomes was present in the non‐producer clone. This may be due to the presence in the non‐producer cells of the constant region χ‐chain fragment. In order to determine the relative synthesis rate of χ and γ mRNAs, pulse‐labeled polysomes were immune precipitated using antibodies to χ and γ chains. It was found that χ and γ mRNA molecules are produced at a very high relative rate each accounting for 10–15% of the total labeled mRNA after 1 h of labeling. These values are higher than the steady‐state pool size of χ and γ mRNA, which was 5–6%, and indicates that the half‐life of these molecules is not unusually high. It is concluded that the amplified synthesis of immunoglobulin chains in myeloma cells is mainly due to a high rate of production of translatable χ and γ mRNAs.

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Membrane Ig on MPC11 myeloma cells: correlation between the expression of membrane Ig, a receptor for Ig and the process of secretion

Corte¹,

Risso

Ferrarini

et al. 1976

Eur J Immunol

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The expression of membrane immunoglobulin (mIg) was examined in three cloned MPC11-derived mouse myeloma cell lines. Membrane immunofluorescence studies demonstrated that IgG2b producer cells (P1) had complete IgG molecules, L-chain producer (L1) had only L-chain determinants and nonproducer (NP2) did not have any Ig determinants on the cell surface. An Ig receptor, with characteristics different from B lymphocyte Fc receptor, has been found to be present on secreting cells (P1 or L1), but not on the NP2 cell variant. The data reported in the present paper indicate that the expression of mIg and of the Ig receptor molecule is clearly correlated with the process of secretion. In the light of previous data reported on Ig secretion, a model is proposed which correlates the process of secretion with the expression not only of mIg, but also of the receptor for Ig.

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Independent Synthesis of Light and Heavy Chains

Cited by 19 publications

References 22 publications

Mutations Affecting the Structure and Function of Immunoglobulin M

Mutations Affecting the Structure and Function of Immunoglobulin M

A High Production Rate of Translatable IgG mRNA Accounts for the Amplified Synthesis of IgG in Myeloma Cells

Membrane Ig on MPC11 myeloma cells: correlation between the expression of membrane Ig, a receptor for Ig and the process of secretion

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