Springer, T.A. & Strominger, J.L. Detergent-soluble products of the HLA region. Transplant. Proc. 9, (Suppl. 1), 21-28 (1977). Springer_1977_2438.pdf
Springer, T.A., Kaufman, J.F., Terhorst, C. & Strominger, J.L. Purification and structural characterisation of human HLA-linked B-cell antigens. Nature 268, 5617, 213-218 (1977).Abstract

The human B cell-specific alloantigen which is closely linked genetically to HLA contains two non-covalently associated, sialogycoprotein subunits of molecular weight (MW) 29,000 (p29), and 34,000 (p34). Although p29 and p34 have different amino-terminal sequences, their tyrosine peptide maps indicate considerable similarity in other portions of their polypeptide chains. Thus the genes for their proteins may have evolved by duplication of a common ancestral gene. Another lymphocyte cell surface protein of MW 16,000 (p16) has also been characterised. Both p16 and p44 (the heavy chain of HLA-A,B antigens) have been compared with p29 and p34.

Springer, T.A., Kaufman, J.F., Siddoway, L.A., Mann, D.L. & Strominger, J.L. Purification of HLA-linked B lymphocyte alloantigens in immunologically active form by preparative sodium dodecyl sulfate-gel electrophoresis and studies on their subunit association. J. Biol. Chem. 252, 6201-6207 (1977).Abstract

The HLA-linked B cell alloantigen (p29,34) is composed of two subunits of 29,000 (p29) and 34,000 (p34) molecular weight. The partially purified HLA-linked B cell alloantigen was purified by a final step of preparative sodium dodecyl sulfate-gel electrophoresis. An antiserum was prepared against p29,34 which specifically lysed B lymphocytes. In sodium dodecyl sulfate at 21 degrees, p29 and p34 remained noncovalently associated and retained immunologic activity; subunit dissociation at higher temperatures correlated with loss of immunologic activity. Although the pI values of p29 and p34 are 6.1 and 5.2, respectively, the subunits co-electrofocus under nondenaturing conditions. In addition, cross-linking studies showed the B cell antigen has a (p29)1(p34)1 subunit structure.

Strominger, J.L., et al. Structure of HLA-A and HLA-B antigens isolated from cultured human lymphocytes. Cold Spring Harbor Symp. Quant. Biol. 41, 323-329 (1977).Abstract

From these data, a model was prepared which summarizes schematically our present knowledge of the structure and orientation of the HL-A antigenic molecule in the lymphocyte membrane (Fig. 3). It seems likely that the heavy chain spans the membrane, with the hydrophobic region inserted in the membrane and the hydrophilic C-terminus inside the cell. This C-terminal region bears one (possible two) SH residue which has the potential for forming interchain disulfides. Whether or not these are actually formed physiologically remains an interesting question. There is the attractive possibility that whatever the physiological functions of HL-A antigens are, structurally these molecules provide the potential for signaling from outside the cell to inside the cell because they span the membrane. It is even conceivable that this function might be expressed via the opening and closing of disulfide bridges.

Springer, T.A., Robb, R.J., Terhorst, C. & Strominger, J.L. Subunit and disulfide structure of monomeric and dimeric forms of detergent-soluble HLA antigens. J. Biol. Chem. 252, 4694-4700 (1977).Abstract

The structure of monomeric and disulfide-bonded dimeric forms of HLA antigens has been studied. Detergent-soluble HLA antigen heavy chains contain one or two easily reduced sulfhydryl groups not found in papain-solubilized HLA antigens, as demonstrated by amino acid analysis (Springer, T. A., and Strominger, J.L. (1976) Proc. Natl. Acad. Sci. U.S.A. 73, 2481-2485, and Terhorst, C., Parham, P., Mann, D.L., and Strominger, J.L. (1976) Proc. Natl. Acad. Sci. U.S.A. 73, 910-914) and by labeling with iodo[3H]acetate. Dimer formation occurred during purification, since it was prevented by pretreatment of membranes containing HLA antigen with iodoacetamide. Cross-linking studies showed that the non-disulfide-bonded form of HLA antigens contains one subunit each of the Mr = 44,000 heavy chain and the Mr = 12,000 light chain (beta2-microglobulin).

Springer, T.A. & Strominger, J.L. Detergent-soluble HLA antigens contain a hydrophilic region at the COOH-terminus and a penultimate hydrophobic region. Proc. Natl. Acad. Sci. U. S. A. 73, 2481-2485 (1976).Abstract

Purified, detergent-soluble HLA antigens (p44,12) are composed of a glycoprotein of molecular weight 44,000 (p44) and a peptide of molecular weight 12,000 (p12), beta2-microglobulin. Upon digestion with papain, p44,12 is converted to p39,12, then to p34,12, which retains antigenic activity. The NH2-terminal amino acid sequences of p34 and p44 are identical. p44, p39, and p34 were purified, and comparison of their amino acid compositions showed that the COOH-terminal peptide removed by the first papain cleavage is hydrophilic and contains cysteine that can be alkylated after mild reduction. The penultimate COOH-terminal peptide removed by the second papain cleavage is hydrophobic, and presumably anchors HLA antigens to the membrane. This correlates with the observation that p44,12 and p39,12 bind detergent, while p34,12 does not. The orientation and integration of HLA antigensin the lymphocyte membrane were thus defined, and the structure suggests that HLA antigens span the plasma membrane.

Strominger, J.L., et al. The immunoglobulin-like structure of human histocompatibility antigens. Federation Proceedings 35, 1177-1182 (1976). Strominger_2126.pdf
Strominger, J.L., et al. Isolation and structure of products of the human histocompatibility gene complex. Role of histocompatibility gene complex in immune responses. Proc. Int. Conf. at Brook Lodge, Mich. 35, 621-643 (1976). Strominger_1976_2436.pdf
Strominger, J.L., et al. The structure of products of the major histocompatibility complex in man. 27. Mosbach Colloquium: The immune system 202-219 (1976). Strominger_1976_2437.pdf
Strominger, J.L., et al. The immunoglobulin-like structure of human histocompatibility antigens. Transplantation Reviews 21, 126-143 (1974). strominger_1974_356.pdf
Cresswell, P., et al. Immunological identity of the small subunit of HL-A antigens and β2-microglobulin and its turnover on the cell membrane. Proceedings of the National Academy of Sciences of the United States of America 71, 2123-2127 (1974).Abstract

A number of immunological methods have been employed to show that the small subunit of HL-A antigens, isolated either after papain treatment or after solubilization with detergent, is identical to beta(2)-microglobulin, a protein previously isolated from human urine and shown to be homologous in structure to constant region domains of immunoglobulins. Moreover, quantitative data indicate virtually total identity between the small subunit of HL-A antigens and beta(2)-microglobulin. Studies of the turnover of labeled HL-Aantigens from the lymphocyte surface indicate that the two subunits turn over at similar rates, although only the small subunit could be detected in the culture medium. The significance of these observations is discussed.

Springer, T.A., Strominger, J.L. & Mann, D. Partial purification of detergent solubilized HL-A antigen and its cleavage by papain. Proceedings of the National Academy of Sciences of the United States of America 71, 1539-1543 (1974).Abstract

HL-A antigen solubilized with the non-ionic detergent, Brij 99, has been purified to about 50% of homogeneity from a cultured human lymphoblast line. It consists of two nonidentical subunits of 44,000 and 12,000 molecular weight (MW). Upon papain proteolysis the 44,000 MW peptide is converted by at least two cleavages to a 34,000 MW peptide, but the 12,000 MW peptide appears to be unchanged. Concomitantly, the apparent molecular weight in gel filtration chromatography under nondenaturing conditions in the presence of Brij 99 is reduced from 460,000 to 45,000. HL-A molecules produced by direct papain proteolysis of membranes and bypapain treatment of purified detergent-soluble HL-A are identical.

Grey, H.M., et al. The small subunit of HL-A antigens is β2-microglobulin. Journal of Experimental Medicine 138, 1608-1612 (1973). grey_1973_928.pdf