Biochemical analysis of an MHC-linked hematopoietic cell surface antigen, Qa-2
✍ Scribed by Soloski, Mark J. ;Vitetta, Ellen S. ;Flaherty, Lorraine ;Uhr, Jonathan W.
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1981
- Tongue
- English
- Weight
- 613 KB
- Volume
- 16
- Category
- Article
- ISSN
- 0275-3723
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✦ Synopsis
Abstract
The region of the murine 17th chromosome telomeric to H‐2D encodes a group of serologically defined cell surface antigens termed Qa‐1‐5. These antigens are of interest because their expression is restricted to hematopoietic cells. In addition, the molecular weight and subunit structure (ie, association with β‐2 microglobulin) of Qa‐2 molecules are similar to H‐2 and TL antigens. In the present studies, we have prepared isotopically labeled Qa‐2 and H‐2 molecules from mitogen‐stimulated C57BL/6 spleen cells. Comparative peptide mapping of tryptic peptides from Qa‐2 and H‐2 molecules (K^b^, D^b^K^k^, D^d^) reveal that Qa‐2 has a unique primary structure. However, considerable homology is indicated since 30–40% of the Qa‐2 peptides cochromatograph with peptides derived from H‐2K^b^, H‐2D^b^, H‐2K^k^, and H‐2D^d^. Studies by other investigators have demonstrated that similar levels of structural homology are observed when H‐2K, H‐2D, and H‐2L tryptic peptides are analyzed. We conclude from these studies that the Qa‐2 alloantigen is structurally related to a class of cell surface molecules (ie, H‐2) that play critical roles in immune recognition processes. These data further suggest that the genes encoding Qa‐2 and H‐2 molecules have arisen from a common primordial gene.