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J H Freed

Publications and source records attributed to J H Freed.

84 records · Page 5Linked to original sources
PubMed1976

Localization of the papain cleavage site of H-2 glycoproteins.

The antigenic products of the murine H-2K and H-2D genes are glycoproteins of about 45,000 molecular weight which are tightly integrated within the cell surface membrane. A glycoprotein fragment (FAg, antigenic fragment) of 37,000 daltons carrying the carbohydrate, antigenic sites, and the associated putative beta2-microglobulin of 12,000 daltons can be generated by papain cleavage either of the native molecules in the cell membrane or of immune precipitates made from the antigen solubilized by nonionic detergent. Partial NH2-terminal sequence analyses of the native H-2 glycoprotein and of the papain-cleaved glycoprotein fragment establish that the fragment is, in fact, the NH2-terminal portion of the native molecule. Thus, the cleavage by papain proteolysis is near the COOH-terminus, and removal of the COOH-terminal portion (Fm, membrane fragment) converts the glycoprotein to a water-soluble form. This observation suggests that the NH2-terminus of the native glycoprotein extends out of the hydrophobic bilayer of the cell membrane, and that the COOH-terminus contains the membrane binding region and is buried within the bilayer.

Amino Acid Sequence↗
PubMed1976

Mapping of the genetic control of murine response to low doses of the dinitrophenyl conjugates of ovomucoid and bovine gamma-globulin.

The antibody responses in mice to low doses of the DNP-conjugates of ovomucoid (OM) and bovine gamma-globulin (BGG) were measured for a number of inbred strains carrying independent and recombinant H-2 haplotypes. This permitted mapping the gene(s) controlling the response to low doses of OM (Ir-1-OM) within the I-A subregion of the H-2 complex. Similarly, it was possible to map the primary gene(s) controlling the response to low doses of BGG (Ir-1-BGG) within the I-A and/or I-B subregions. Further localization of the Ir-1-BGG gene(s) to the I-A or I-B subregion of the H-2 complex was not possible due to the ambiguous response of the B10.A(4R) strain of mice.

Animals↗
PubMed1975

Quantitative separation of antigen-specific murine antibodies by anti-allotype chromatography.

The use of Sepharose-conjugated murine anti-Iga or anti-Igb allo-antisera allowed the quantitative separation of immunoglobulins of the two allotypes. After fractionation of mixtures of anti-(T,G)-A--L antisera obtained from congenic strains differing in immunoglobulin allotype, it was possible to measure the antigen-binding capacity of specific anti-(T,G)-A--L antibodies in each allotype fraction. Analysis of artificial mixtures of immune sera obtained from homozygous Iga and Igb animals showed that this method is quantitative and internally consistent. This method of affinity chromatography was used in the analysis of specific anti (T,G)-A--L antisera from tetraparental mice.

Animals↗
PubMed1974

Genetic control of the antibody response to poly-L(Tyr,Glu)-poly-D,L-Ala--poly-L-Lys in C3H--CWB tetraparental mice.

In order to further delineate the mechanisms underlying genetic unresponsiveness, tetraparental mice were constructed from immune response-1A gene high responder and low responder parental genotypes, then were immunized with poly-L-(Tyr,Glu)-poly-D,L-Ala--poly-L-Lys ((T,G)-A--L). An analysis of the total serum allotype mixture and of the antigen-binding capacity of the separated allotypes demonstrated that in the milieu of a tetraparental mouse, both high and low responder B cells could be stimulated equally to produce identical high titered anti-(T,G)-A--L responses. Furthermore, these studies show that effective stimulation could occur across a histocompatibility disparity.

Animals↗
PubMedDate not supplied

Immunoglobulin-like nature of the alpha-chain of a human T-cell antigen/MHC receptor.

Although the receptor with which T cells bind specific antigen can, like immunoglobulin, distinguish between antigens which differ only slightly in structure, it is unique in recognizing antigen only in conjunction with one of the self proteins of the major histocompatibility complex (MHC restriction). The receptor was identified and characterized in mouse and man by using monoclonal antibodies to receptor idiotypes, and consists of two disulphide-linked polypeptides, and acidic alpha-chain and a neutral to slightly basic beta-chain. Peptide maps have shown that, like immunoglobulin, both chains vary for receptors of different specificities. T-cell-derived cDNA clones have recently been identified in mouse and man encoding immunoglobulin-like molecules. These were identified as derived from beta-chain genes through a partial N-terminal protein sequence of the beta-chain isolated from a human T-cell tumour. We have now purified the alpha- and beta-chains of the receptor of the human T-cell leukaemia line HPB-MLT, and have determined the amino acid sequence of several tryptic peptides derived from each chain. Our results further confirm that the previously reported cDNA clones encode beta-chains. The sequence of the alpha-chain peptides identify this as another immunoglobulin-like polypeptide chain. Particularly striking was an alpha-chain peptide with high homology to the conserved portion of the immunoglobulin J segment and T-cell receptor beta-chains. Surprisingly, the alpha-chain peptides show little similarity to the sequence predicted by two overlapping putative murine alpha-chain cDNA clones.

Amino Acid Sequence↗
PubMedDate not supplied

Peptide sequences of T-cell receptor delta and gamma chains are identical to predicted X and gamma proteins.

Although most mature peripheral T lymphocytes express a major histocompatibility complex restricted, CD3-associated, antigen receptor (TCR) which has been well characterized, some T cells carry a different CD3-associated heterodimer on their surface. One of the two disulphide-linked chains of this putative second receptor, which in mice has relative molecular mass (Mr) 35,000 (35K), has been identified as a product of the group of gamma genes. The other chain, termed delta (Mr 45K in mice), is not as well characterized. Although gamma/delta-bearing cells are a minor subset among peripheral T lymphocytes, they are the only CD3+ cells in the thymus early in ontogeny. Taking advantage of these kinetics, we have generated gamma/delta-bearing hybridomas, using a new TCR alpha chain-negative variant of the AKR thymoma BW5147 as tumour parent, fetal thymocytes as normal cell partners, and an anti-CD3 monoclonal antibody (mAb) as screening reagent. Gamma and delta chains from one of these hybrids have been purified and partially sequenced. The sequences obtained indicate that delta is indeed identical to the polypeptide encoded by the recently described gene X, as suggested by Chien et al.

Amino Acid Sequence↗