The protein encoded by this gene contains a leucine-rich repeat (LRR). It specifically interacts with TNFRSF9/4-1BB, a member of the tumor necrosis factor receptor (TNFR) superfamily. Overexpression of this gene suppresses the activation of NF-kappa B induced by TNFRSF9 or TNF receptor-associated factor 2 (TRAF2), which suggests that this protein is a negative regulator of TNFRSF9-mediated signaling cascades. At least three alternatively spliced transcript variants encoding distinct isoforms have been observed.