# CELLULAR AND STRUCTURAL STUDIES OF MYELOMA MUTANTS

> **NIH NIH R01** · ALBERT EINSTEIN COLLEGE OF MEDICINE · 1987 · $249,217

## Abstract

My research interests focus on examining several variants of the MPC 11
IgG2b-producing mouse myeloma cell lines which synthesize altered immunoglobulin
heavy chains.  Some altered heavy chains are shorter than the parent, having
molecular weights of 50,000 or 40,000 compared to the parental size of 55,000;
others have serological, peptide and assembly characteristics of a new subclass,
IgG2a.  The latter are especially interesting because they represent the
expression of a previously silent constant region gene.  We are studying the
structural relationships of these variants to each other, to the parental MPC11,
and to MOPC 173, and IgG2a protein of known sequence.  We have shown that the
several IgG2a variant proteins retain the parental idiotype, yet differ from
each other by peptide maps, charge and assembly parameters.  These same
parameters have enabled us to subgroup the variants.  Analytical techniques of
papain digestion products such as immunoelectrophoresis, SDS-PAGE of CNBr
fragments, and comparative peptide maps, in addition to partial primary
structural analysis have shown that the Fc of one variant protein is entirely
gamma2a-like while the Fc of a second is a gammma2b-gamma 2a hybrid.
Characterization of these and other variants gives us tools to localize mouse
heavy chain allotypic determinants, to probe the molecular requirements for
macrophage Fc receptor interactions, and to define molecular events in
secretion.  The findings that indicate that some variants seem to make a
recombinant heavy chain and that gamma2a and gamma2b constant regions have
extensive homology raise the question of whether gene rearrangements are
occurring in these cells.  We will prepare restriction enzyme fragments from
genomic DNA of parent and variant cells and examine them by hybridization with
subclass-specific cDNA probes to see if the patterns of hybridization differ.
In addition, we will approach the question of the action of mutagens in these
cells by asking whether after treatment with drugs such as ICR-191 or Melphalan,
recombination is enhanced, or any gross chromosomal abnormalities are occurring.

## Key facts

- **NIH application ID:** 3125450
- **Project number:** 5R01AI013509-12
- **Recipient organization:** ALBERT EINSTEIN COLLEGE OF MEDICINE
- **Principal Investigator:** Barbara Birshtein
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1987
- **Award amount:** $249,217
- **Award type:** 5
- **Project period:** 1976-06-30 → 1989-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3125450

## Citation

> US National Institutes of Health, RePORTER application 3125450, CELLULAR AND STRUCTURAL STUDIES OF MYELOMA MUTANTS (5R01AI013509-12). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3125450. Licensed CC0.

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