Abstract
Major histocompatibility complex (MHC) class I molecules are heterodimers of a class I heavy chain and β2-microglobulin that bind peptides supplied by the MHC region-encoded transporters associated with antigen processing (TAP). Peptide binding by class I heterodimers is necessary for their maturation into stable complexes and is dependent on their physical association with TAP. In human mutant 721.220 cells, however, a novel genetic defect causes the failure of class I heterodimers to associate with TAP. This deficiency correlates with lack of expression of a glycoprotein, tapasin (TAP-associated glycoprotein), which has been found in association with class I heterodimers and TAP. Employing a transcomplementation analysis, we obtained evidence co-localizing the genetic defect of mutant 220 cells and the structural or a regulatory gene controlling the expression of tapasin on the short arm of chromosome 6, which includes the MHC. Expression of tapasin and the normal interaction of class I heterodimers with TAP are concomitantly restored, indicating the probable function of tapasin as a physical link between these complexes. In further support of this model, the absence of tapasin in mutant 220 cells correlates with reduced class I heterodimer stability, suggesting that tapasin may stabilize class I heterodimers and thereby enhance their association with TAP. These results further implicate tapasin in a mechanism that promotes peptide binding by class I heterodimers through their interaction with TAP.
Similar content being viewed by others
Author information
Authors and Affiliations
Additional information
Received: 20 March 1997 / Revised: 2 June 1997
Rights and permissions
About this article
Cite this article
Grandea III, A., Lehner, P., Cresswell, P. et al. Regulation of MHC class I heterodimer stability and interaction with TAP by tapasin. Immunogenetics 46, 477–483 (1997). https://doi.org/10.1007/s002510050308
Issue Date:
DOI: https://doi.org/10.1007/s002510050308