| Autor: |
Griffith, I J, Ghogawala, Z, Nabavi, N, Golan, D E, Myer, A, McKean, D J, Glimcher, L H |
| Zdroj: |
Proceedings of the National Academy of Sciences of the United States of America; July 1988, Vol. 85 Issue: 13 p4847-4851, 5p |
| Abstrakt: |
The association of foreign antigen with Ia molecules on the surface of antigen-presenting cells is necessary for the interaction with the clonally distributed antigen receptor on T cells and is therefore critical in the initiation and regulation of immune responses. Ia polypeptides (alpha and beta) are composed of two extracellular domains, a transmembrane domain and a cytoplasmic domain. Although exon-shuffling experiments have demonstrated that antigen associates with the NH2-terminal alpha 1 and beta 1 domains, the roles that the other domains play in Ia function are still poorly understood. The B-hybridoma cell line 2B1 was selected in a series of positive and negative immunoselection steps for a mutation in the Ek alpha polypeptide. It was found to fortuitously contain a mutation in the Ak alpha polypeptide as well. Sequence analysis of the Ak alpha gene showed that a single base transition (C----T) resulted in a stop codon at amino acid residue 222. This caused the loss of 12 amino acids from the cytoplasmic domain of the mature polypeptide. This mutation results in a decreased level of Ak alpha polypeptide expression on the cell surface (50% of wild-type levels), an increased half-life of Ak alpha polypeptide in the cell, and a specific limited defect in antigen presentation. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
|
