Uniquely Conformed Peptide-Containing β2-Microglobulin- Free Heavy Chains of HLA-B2705 on the Cell Surface

Unassembled (free) heavy chains appear during two stages of the class I MHC molecule's existence: immediately after translation but before assembly with peptide and β2-microglobulin, and later, upon disintegration of the heterotrimeric complex. To characterize the structures of folding and degradation intermediates of the class I heavy chain, three monoclonal antibodies have been produced that recognize epitopes along the H-2Kb heavy chain which are obscured upon proper folding and subsequent assembly with β2-microglobulin (KU1: residues 49-54; KU2: residues 23-30; KU4: residues 193-198). The Kb heavy chain is inserted into the lumen of the endoplasmic reticulum in an unfolded state reactive with KU1, KU2, and KU4. Shortly after completion of the polypeptide chain, reactivity with KU1, KU2 and KU4 is lost synchronously, suggesting that folding of the class I heavy chain is a rapid, cooperative process. Perturbation of the folding environment in intact cells with the reducing agent dithiothreitol or the trimming glucosidase inhibitor N-7-oxadecyl-deoxynojirimycin prolongs the presence of mAb-reactive Kb heavy chains. At the cell surface, a pool of free Kb heavy chains appears after 60–120 min of chase, whose subsequent degradation, but not their initial appearance, is impaired in the presence of concanamycin B, an inhibitor of vacuolar acidification. Thus, free heavy chains that arise at the cell surface are destroyed after internalization.

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Dissociation of β2-microglobulin leads to the accumulation of a substantial pool of inactive class I MHC heavy chains on the cell surface

Cell ◽

10.1016/0092-8674(91)90093-e ◽

1991 ◽

Vol 65 (4) ◽

pp. 611-620 ◽

Cited By ~ 80

Author(s):

Kenneth L. Rock ◽

Sandra Gamble ◽

Lisa Rothstein ◽

Colette Gramm ◽

Baruj Benacerraf

Keyword(s):

Cell Surface ◽

Class I ◽

Class I Mhc ◽

Β2 Microglobulin ◽

Heavy Chains

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Demonstration of a murine cell surface component with affinity for exogenous β2-microglobulin

European Journal of Immunology ◽

10.1002/eji.1830091210 ◽

1979 ◽

Vol 9 (12) ◽

pp. 964-971 ◽

Cited By ~ 16

Author(s):

Karin Sege ◽

Lars Östberg ◽

Per A. Peterson

Keyword(s):

Cell Surface ◽

Murine Cell ◽

Β2 Microglobulin ◽

Surface Component ◽

Cell Surface Component

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Fate of surrogate light chains in B lineage cells.

Journal of Experimental Medicine ◽

10.1084/jem.183.2.421 ◽

1996 ◽

Vol 183 (2) ◽

pp. 421-429 ◽

Cited By ~ 38

Author(s):

K Lassoued ◽

H Illges ◽

K Benlagha ◽

M D Cooper

Keyword(s):

B Cells ◽

Cell Surface ◽

Light Chain ◽

Light Chains ◽

Receptor Complex ◽

Surrogate Light Chain ◽

Heavy Chains ◽

Receptor Component ◽

B Lineage ◽

Receptor Assembly

Biosynthesis of the immunoglobulin (Ig) receptor components and their assembly were examined in cell lines representative of early stages in human B lineage development. In pro-B cells, the nascent surrogate light chain proteins form a complex that transiently associates in the endoplasmic reticulum with a spectrum of unidentified proteins (40, 60, and 98 kD) and Bip, a heat shock protein family member. Lacking companion heavy chains, the surrogate light chains in pro-B cells do not associate with either the Ig(alpha) or Ig(beta) signal transduction units, undergo rapid degradation, and fail to reach the pro-B cell surface. In pre-B cells, by contrast, a significant portion of the surrogate light chain proteins associate with mu heavy chains, Ig(alpha), and Ig(beta) to form a stable receptor complex with a relatively long half-life. Early in this assembly process, Bip/GRP78, calnexin, GRP94, and a protein of approximately 17 kD differentially bind to the nascent mu heavy chains. The 17-kD intermediate is gradually replaced by the surrogate light chain protein complex, and the Ig(alpha) and Ig(beta) chains bind progressively to the mu heavy chains during the complex and relatively inefficient process of pre-B receptor assembly. The results suggest that, in humans, heavy chain association is essential for surrogate light chain survival and transport to the cell surface as an integral receptor component.

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Functional cell surface expression by a recombinant single-chain class I major histocompatibility complex molecule with acis-active β2-microglobulin domain

European Journal of Immunology ◽

10.1002/eji.1830241110 ◽

1994 ◽

Vol 24 (11) ◽

pp. 2633-2639 ◽

Cited By ~ 15

Author(s):

Li Lee ◽

Louise McHugh ◽

Randall K. Ribaudo ◽

Steven Kozlowski ◽

David H. Margulies ◽

...

Keyword(s):

Major Histocompatibility Complex ◽

Cell Surface ◽

Complex Molecule ◽

Major Histocompatibility Complex Molecule ◽

Surface Expression ◽

Class I ◽

Cell Surface Expression ◽

Single Chain ◽

Β2 Microglobulin ◽

Histocompatibility Complex

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Abrogation of cell surface expression of human class I transplantation antigens by an adenovirus protein in Xenopus laevis oocytes.

The Journal of Cell Biology ◽

10.1083/jcb.101.2.540 ◽

1985 ◽

Vol 101 (2) ◽

pp. 540-547 ◽

Cited By ~ 16

Author(s):

L Severinsson ◽

P A Peterson

Keyword(s):

Cell Surface ◽

Heavy Chain ◽

Viral Protein ◽

Surface Expression ◽

Class I ◽

Cell Surface Expression ◽

Xenopus Laevis Oocytes ◽

Human Class ◽

Heavy Chains ◽

Transplantation Antigens

Class I transplantation antigens form complexes with a virus protein encoded in the early region E3 of the adenovirus-2 genome. The interaction between this viral glycoprotein, E19, and nascent human class I antigens has been examined by microinjecting purified mRNA into Xenopus laevis oocytes. Both E19 and the two class I antigen subunits, the heavy chain and beta 2-microglobulin (beta 2M), were efficiently translated. The heavy chains did not become terminally glycosylated, as monitored by endoglycosidase H digestion, and were not expressed on the oocyte surface unless they were associated with beta 2M. The E19 protein did not become terminally glycosylated, and we failed to detect this viral protein on the surface of the oocytes. Co-translation of heavy chain and E19 mRNA demonstrated that the two proteins associate intracellularly. However, neither protein appeared to be transported to the trans-Golgi compartment. Similar observations were made in adenovirus-infected HeLa cells. Heavy chains bound to beta 2M became terminally glycosylated in oocytes in the presence of low concentrations of E19. At high concentrations of the viral protein, no carbohydrate modifications and no cell surface expression of class I antigens were apparent. Thus, beta 2M and E19 have opposite effects on the intracellular transport of the heavy chains. These data suggest that adenovirus-2 may impede the cell surface expression of class I antigens to escape immune surveillance.

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