Analysis of EST clones and use of a signal sequence trap screening of the murine brain have led to identification of a new member of the tumor necrosis factor receptor superfamily designated as TAJ and TROY, respectively (1,2).
TAJ/TROY is a membrane protein of 423 amino acids with characteristic cysteine-rich motifs in the extracellular domain and a tumor necrosis factor receptor-associated factor 2 (TRAF2) binding sequence in the cytoplasmic domain.
Human TROY has 78% identity at the amino acid level with mouse TROY.
The extracellular domain of TROY has significant homology with that of EDAR (another newly identified receptor belonging to TNF receptor family) that specifies hair follicle fate (3).
The cytoplasmic domain of TAJ is different from other TNF receptor family members.
Although its cytoplasmic domain does not contain death domain, TAJ/TROY induced cell death is probably mediated through a caspase-independent pathway.
TAJ-induced JNK activation was not blocked by dominant-negative inhibitors of TRAF2, TRAF5, or ASK1, which have been previously implicated in JNK activation via TNFR1 and CD40.
However, co-immunoprecipitation assays revealed that TAJ is capable of binding a number of different TRAF family members, and it is possible that TAJ-induced JNK activation is mediated by an as yet untested TRAF homolog, such as TRAF6.
TROY mRNA is highly expressed in brain, prostate and embryo and moderately expressed in the heart, lung, liver.
