Abstract
Among the best characterized non-classical mouse major histocompatibility antigens are the Qa-2 molecules. These proteins can serve as targets for allogenic cytotoxic T cells and as signal transducing molecules. They are structurally similar to H-2 transplantation antigens in their Ntarminal and β2-microglobulin binding domains but differ at their C-termini. While the H-2 antigens span the cell membrane, the Qa-2 molecules are attached to the cell surface via phospholipid anchors. The genetic information encoding this attachment is contained in exon 5. In concanavalin A activated splenocytes the expression of membrane bound Qa-2 antigens declines and, simultaneously, soluble forms of Qa-2 molecules are secreted. We demonstrate here that the soluble Qa-2 polypeptides are translated from alternatively spliced mRNAs lacking exon 5, while the membrane forms are encoded by the full-size transcripts. In cultured cells the alternative splicing of the Qa-2 message is induced by Tcell activation with concanavalin A. The canonical mRNA encoding the membrane form of Qa-2 predominates in unstimulated mouse tissues but the cultured cell lines, like activated T cells, express enhanced levels of the truncated mRNA. In some cell lines almost all Qa-2 transcripts lack exon 5. For example, in L cells, mRNAs encoding soluble Qa-2 molecules are at least 10 times more abundant than Qa-2 transcripts encoding phospholipid anchored antigens. These findings are discussed in terms of potentlal functions of membrane bound and secreted Qa-2 molecules.
Original language | English (US) |
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Pages (from-to) | 3839-3847 |
Number of pages | 9 |
Journal | EMBO Journal |
Volume | 9 |
Issue number | 12 |
State | Published - 1990 |
Keywords
- Activated T cells
- Alternative splicing
- Major histocompatibility complex
- Qa-2 molecules
ASJC Scopus subject areas
- General Immunology and Microbiology
- General Biochemistry, Genetics and Molecular Biology
- Molecular Biology
- General Neuroscience