GENE STRUCTURE AND CHROMOSOMAL LOCALIZATION OF THE MOUSE HOMOLOG OF RAT OX40 PROTEIN

The OX40 protein is expressed only on activated rat CD4(+) T blasts an d is a member of a superfamily of cell surface molecules which include s CD40, CD30, CD95 (Fas), CD27, 4-1BB antigens and the receptors for t umor necrosis factor (TNF) and nerve growth factor (NGF). The proteins of this group are related to each other by having three to six repeat s of a cysteine-rich sequence in their extracellular domains. Members of this family of receptors have also been shown to bind to ligands wh ich are structurally related to TNF. The mouse homologue of the rat OX 40 protein was cloned at the cDNA and genomic levels. The gene structu re shows that there are several intron/exon borders shared between OX4 0 and CD27, CD40,TNF receptor type I, CD95 and 4-1BB genes. This group of genes is less closely related structurally to the gene structure o f the NGF receptor. The gene encoding murine OX40 has been placed on m ouse chromosome 4, in an area which contains the genes for TNF recepto r type II and 4-1BB, and is syntenic with a region of human chromosome 1 which contains human TNF receptor type II, OX40, and CD30 genes.