Effect of a tapasin mutant on the assembly of the mouse MHC class I molecule H2‐K d

• Published in: Immunology and cell biology 2009-08, Vol.88 (1), p.57-62
• Main Authors: Simone, Laura C, Wang, Xiaojian, Tuli, Amit, Solheim, Joyce C
• Format: Article
• Language: English
• ISSN: 0818-9641; 1440-1711
• DOI: 10.1038/icb.2009.59

Major histocompatibility complex (MHC) class I heavy chain/β 2 m heterodimers assemble with antigenic peptides through interactions with peptide‐loading complex proteins, including tapasin and ERp57. In human cells, a cysteine residue within tapasin (C95) has been shown to form a covalent bond with ERp57. In this study, we focused on the effect of this tapasin amino‐acid residue in mouse cells expressing the MHC class I molecule H2‐K d . We showed that a large disulfide‐bonded complex was present in the mouse cells that included ERp57, tapasin, and K d . Furthermore, in mouse cells, unlike human cells, we found that tapasin mutated at C95 can participate in a non‐covalent complex with ERp57. Comparison of our findings to earlier findings with a human molecule (HLA‐B ∗ 4402) also revealed that a tapasin C95 mutation has a stronger effect on the maturation and stability of K d than HLA‐B ∗ 4402. Overall, our results characterize the influence of this tapasin cysteine residue on the stable surface expression of a mouse MHC class I molecule and reveal differences in tapasin C95 interactions and effects between mouse and human systems.