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Biomedical subjects

J D Capra

Publications and source records attributed to J D Capra.

At least 217 records · Page 12Linked to original sources
PubMed1980

Structural studies on the murine Ia alloantigens. VII. Further evidence for two-gene control of the E/C alloantigens.

By utilizing comparative tryptic peptide analysis of the E/C alloantigens from additional H-2 recombinant strains, the gene encoding the E/C beta subunit was localized to the I-A or B subregions. By peptide mapping techniques, the E/C alpha- and beta-chains showed little structural homology with the A alloantigen alpha and beta subunits. In addition, comparisons of the E/C beta subunits from F1 strains (b x d) with those from both parental strains revealed that in a heterozygote the beta subunit from either allele (b or d) can associate with the alpha-chain from one allele (d). Thus, the formation of hybrid E/C antigens by cis-trans gene complementation increases the E/C alloantigen repertoire in heterozygotes.

Amino Acid Sequence↗
PubMed1980

Structural studies on the murine fourth component of complement (C4). IV. Demonstration that C4 and Slp are encoded by separate loci.

The S region of the murine major histocompatibility complex (MHC) encodes the structural gene for the fourth complement component (C4) and controls C4 serum levels and expression of the sex-limited protein (Slp). Although Slp was first throught to be an allele of C4, more recent studies have suggested that Slp is either a modified product of the C4 locus or is encoded at a separate locus. By using a sensitive peptide analysis technique, each of the three constitutive polypeptide chains of C4 and Slp was compared, and multiple distinct peptides as well as several shared peptides were detected. These results demonstrate that although C4 and Slp undoubtedly share a common genetic origin, they are encoded by separate structural genes.

Alleles↗
PubMed1979

Organization of the immune response genes.

The I region of the major histocompatibility complex contains immune response genes that display considerable polymorphism; that is, there are many alleles at each locus. These genes regulate the immune response to antigen by mediating intercellular communication among lymphoreticular cells. An analysis of the primary structure of the products of two subregions of (I-A, I-E/C) was undertaken in order to understand the genetic organization of the region, the evolution of the genes and, eventually, their function.

Alleles↗
PubMed1979

Studies on the clonal origin of multiple myeloma. Use of individually specific (idiotype) antibodies to trace the oncogenic event to its earliest point of expression in B-cell differentiation.

IgA myeloma proteins of kappa- and lambda-types were isolated from two patients. These were used to produce and purify anti-idiotype antibodies of both broad (myeloma-related) and narrow (individual myeloma) specificities. The anti-idiotype antibodies were conjugated with fluorochromes and used as immunofluorescent probes to trace in the patients clonal expansion at different levels of B-cell differentiation. Our results (a) confirm that B lymphocyte precursors in IgA plasma-cell myelomas are involved in the malignant process, (b) show that B lymphocytes of the malignant clone include those expressing each of the major heavy-chain isotypes, mu, delta, gamma, and alpha, and (c) provide strong circumstantial evidence that pre-B-cell members of the malignant clone are also increased in frequency. T cells expressing idiotypic determinants were not detected. These findings argue that the initial oncogenic event may occur in a B-stem cell and is not influenced through stimulation by antigen. An interesting association was the increased frequency of related clones of B lymphocytes as detected by their reactivity with anti-idiotype antibodies of broad specificity. Neither plasma cell nor pre-B-cell members of these related clones were increased in frequency. Anti-idiotype antibodies or helper T cells reactive with myeloma-related idiotypes could be responsible for this phenomenon. We discuss other implications of these findings and speculate that all of the various phenotypes of B-lineage malignancies may result from oncogenic processes affecting stem cell targets.

Antibodies, Neoplasm↗
PubMed1979

Structural studies on the murine Ia alloantigens. V. Evidence that the structural gene for the I-E/C beta polypeptide is encoded within the I-A subregion.

The E/C alpha- and beta-subunits of intra-I-region recombinants were analyzed for primary structural variation by comparative tryptic peptide mapping. The E/C alpha-polypeptides from B10.A, B10.A (3R) and B10.A (5R) showed complete coincident elution of peptides; the E/C beta-chains from B10.A and 3R (or 5R) were approximately 40% different. This suggests that the structural gene for the E/C beta-polypeptide is within the I-A subregion.

Amino Acid Sequence↗
PubMed1979

Amino acid sequence analysis of group e allotype-related peptides derived from lagomorph IgG.

A tryptic peptide (T 19) was isolated from a CNBr fragment of IgG from several representatives of present-day lagomorphs including domestic rabbit, hare, cottontail rabbit and pika. The amino acid sequence of this peptide revealed differences which can be correlated with serological polymorphism associated with group e IgG allotypes. The results confirm previous studies establishing the importance of Ala309 for the expression of e 15, particularly the i subspecificity. Arg315 correlates with the expression of the j subspecificity.

Amino Acid Sequence↗
PubMed1979

Studies on murine Ss protein: demonstration that S region encodes structural gene for fourth component of complement.

Although genes controlling the expression of certain complement components have been shown to be linked to the major histocompatibility complex of several species, the structural genes that encode these molecules have been more difficult to map. In this study, the three constitutive polypeptide chains of the fourth component of murine complement (C4) (alpha, beta, and gamma) were isolated from 14 different inbred strains and compared by peptide mapping on analytical sodium dodecyl sulfate gels. The peptide patterns of the alpha and gamma subunits appeared to be nearly identical, but two distinctly different patterns were observed for the C4 beta chain. This structural variant was mapped to the S or G region and, as such, provides direct evidence that a structural gene for a complement component is encoded within a major histocompatibility complex.

Animals↗
PubMed1979

Structural studies on induced antibodies with defined idiotypic specificities. VII. The complete amino acid sequence of the heavy chain variable region of anti-p-azophenylarsenate antibodies from A/J mice bearing a cross-reactive idiotype.

This paper reports the complete amino acid sequence of the variable region of heavy chains derived from A/J anti-p-azophenylarsenate antibodies bearing a cross-reactive idiotype. The structure of this induced idiotypically defined antibody is homogeneous and provides the first direct evidence that heritable idiotypes are defined chemical entities. There are certain similarities between the structure of this murine antibody and the human myeloma protein Eu as well as guinea pig anti-p-azophenylarsonate antibodies. The amino acid sequence of approximately 15% of the constant region of this IgG1 molecule is also described. Combined with our studies of the variable region of the light chains of these molecules, this study represents the first complete V domain structure of an induced idiotypically defined antibody with heritable characteristics.

Amino Acid Sequence↗
PubMed1979

Structural studies on the murine Ia alloantigens. IV. NH2-terminal sequence analysis of allelic products of the I-A and I-E/C subregions.

Murine Ia alloantigens encoded by the I-A and I-E/C subregions were isolated from radiolabeled splenic lysates and examined by NH2-terminal sequence analysis. Haplotype-associated sequence variation was detected in the beta, but not alpha, subunits of both the A and E/C alloantigens. The A beta-polypeptides from k and b haplotypes show four differences in the 12 positions compared, whereas the E/C beta-polypeptides from k and r haplotypes show two differences in the 13 positions compared. No sequence variation was detected between the Ak and Ab alpha-chains (six positions compared) or between the E/Ck and E/Cr alpha-chains (11 positions compared). Homology relationships between these murine Ia alloantigens and the human Ia (DR) alloantigens are also presented.

Alleles↗
PubMed1979

Structural studies on the murine Ia alloantigens. VI. Evidence that both subunits of the I-A alloantigen are encoded by the I-A subregion.

The alpha and beta subunits of the murine I-A alloantigens from several H-2 haplotypes were examined by comparative tryptic peptide mapping by using double label (3H and 14C) techniques. Significant structural variation between alleles was detected in both subunits. Tryptic digests of the alpha polypeptides from s, b, and d showed only 65% co-elution with k; beta-chains from s, b, d, and r were about 50% similar to the k beta subunit. Peptide analysis of the Ak subunits from intra-H-2 recombinant strains indicated that both the alpha and beta polypeptides are encoded within the I-A subregion.

Animals↗