Translin-associated protein X (TSNAX), also called trax, was first identified as a protein that interacts with translin. Subsequent studies demonstrated that these proteins form a heteromeric RNase complex that mediates degradation of microRNAs, a pivotal finding that has stimulated interest in understanding the role of translin and trax in cell signaling. Recent studies addressing this question have revealed that trax plays key roles in both synaptic plasticity and DNA repair signaling pathways. In the context of synaptic plasticity, trax works together with its partner protein, translin, to degrade a subset of microRNAs. Activation of the translin/trax RNase complex reverses microRNA-mediated translational silencing to trigger dendritic protein synthesis critical for synaptic plasticity. In the context of DNA repair, trax binds to and activates ATM, a central component of the double-stranded DNA repair process. Thus, these studies focus attention on trax as a critical signaling protein that interacts with multiple partners to impact diverse signaling pathways. To stimulate interest in deciphering the multifaceted role of trax in cell signaling, we summarize the current understanding of trax biology and highlight gaps in our knowledge about this protean protein.