FIGURE 5.

Biochemical identification of C3H7 antigen as an epithelial CD44 variant containing v3 domain (v3-type variant). A, purified C3H7 antigen from HT29 cells and five sequenced tryptic peptides (red) aligned with human CD44. The transmembrane region is underlined. B, immunoprecipitated product by mAb C3H7 was blotted with the antibodies against various CD44 variants. Note that the C3H7 antigen is recognized by both anti-CD44H and anti-CD44v3 antibodies but not by other anti-CD44 antibodies. C, immunoprecipitated product by anti-CD44v3 mAb was blotted with mAb C3H7, CD44v7, and anti-CD44H, respectively.