Sell^tm2.1Tft

The membrane-proximal region was replaced with DNA encoding a floxed neomycin resistance gene and the 7 amino acid (APVVPTR) membrane-proximal region of mouse E-selectin. It was predicted that this mutation would prevent cleavage of the protein upon cellular activation. Because the presence of the neo resistance gene was found to reduce expression of the gene locus in Selltm2Tft homozygotes, the neo gene was removed by breeding with Cre recombinase transgenic mice. Cell surface levels of mutated protein in homozygote blood, spleen, and lymphocytes was 168%, 214%, and 178%, respectively, of wild-type controls as determined by flow cytometry. Mutated protein was not cleaved from the cell surface upon cellular activation of lymphocytes. (J:142184)