CLONING AND CHARACTERIZATION OF THE 2B4 GENE ENCODING A MOLECULE ASSOCIATED WITH NON-MHC-RESTRICTED KILLING MEDIATED BY ACTIVATED NATURAL-KILLER-CELLS AND T-CELLS

We have recently described a signal transducing molecule, 2B4, express ed on all NK and T cells that mediate non-MHC-restricted killing. The gene encoding this molecule was cloned and its nucleotide sequence det ermined. The encoded protein of 398 amino acids has a leader peptide o f 18 amino acids and a transmembrane region of 24 amino acids. The pre dicted protein has eight N-linked glycosylation sites, suggesting that it is highly glycosylated. Comparison of 2B4 with sequences in the da tabanks indicates that 2B4 is a member of Ig supergene family, and it shows homology to murine and rat CD48 and human LFA-3. Northern blot a nalysis has shown at least three transcripts for 2B4 in adherent lymph okine-activated killer cells of several mouse strains and TCR-gamma/de lta dendritic epidermal T cell lines but not in allospecific T cell cl ones. These three mRNA are the products of differential splicing of he terogeneous nuclear RNA. Southern blot analysis of genomic DNA from se veral mouse strains revealed that 2B4 belongs to a family of closely r elated genes. The 2B4 gene has been mapped to mouse chromosome 1 by an alysis of 2B4 expression in recombinant inbred mouse strains.