Rat tapasin: cDNA cloning and identification as a component of the class I MHC assembly complex.
During the assembly of major histocompatibility complex (MHC) class I molecules transient associations are formed with the endoplasmic reticulum resident chaperones calnexin and calreticulin, ERp57 oxidoreductase, and also with tapasin, the latter mediating binding of the class I molecules to the transporter associated with antigen processing (TAP). We report here the isolation of a cDNA encoding rat tapasin from a DA (RT1av1) library. The cDNA encodes a proline-rich (11.3%) polypeptide of 464 residues with a potential ER-retention KK motif at its COOH-terminus, and a predicted molecular mass of 48 kDa. Matrix-assisted laser-desorption ionisation (MALDI) mass spectrometry of peptides derived from in-gel tryptic digestion of a TAP-associated protein match regions of the predicted translation product. A species of the correct molecular mass and predicted pl was also identified in association with radiolabelled immunoprecipitates of the rat TAP complex analysed by two-dimensional gel electrophoresis. This confirms rat tapasin as a component of the rat MHC class I assembly complex.
Deverson
E V
EV
Molecular Immunology Programme, The Babraham Institute, Cambridge, UK.
Powis
S J
SJ
Morrice
N A
NA
Herberg
J A
JA
Trowsdale
J
J
Butcher
G W
GW
D000595:Amino Acid Sequence; D000818:Animals; D017920:Antiporters / Q000235:genetics*; D003001:Cloning, Molecular; D018076:DNA, Complementary; D015180:Electrophoresis, Gel, Two-Dimensional; D015395:Histocompatibility Antigens Class I / Q000235:genetics*; D006801:Humans; D007136:Immunoglobulins / Q000235:genetics*; D026901:Membrane Transport Proteins; D051379:Mice; D008969:Molecular Sequence Data; D051381:Rats; D017386:Sequence Homology, Amino Acid
D017920:Antiporters; D018076:DNA, Complementary; D015395:Histocompatibility Antigens Class I; D007136:Immunoglobulins; D026901:Membrane Transport Proteins; C107762:tapasin