TRIP13 is a mammalian gene that encodes the thyroid receptor-interacting protein 13. In budding yeast, the analog for TRIP13 is PCH2. TRIP13 is a member of the AAA+ ATPase family, a family known for mechanical forces derived from ATP hydrolase reactions. The TRIP13 gene has been shown to interact with a variety of proteins and implicated in a few diseases, notably interacting with the ligand binding domain of thyroid hormone receptors, and may play a role in early-stage non-small cell lung cancer. However, recent evidence implicates TRIP13 in various cell cycle phases, including meiosis G2/Prophase and during the Spindle Assembly checkpoint (SAC). Evidence shows regulation to occur through the HORMA domains, including Hop1, Rev7, and Mad2. Of note, Mad2's involvement in the SAC is shown to be affected by TRIP13 Due to TRIP13's role in cell cycle arrest and progression, it may present opportunity as a therapeutic candidate for cancers. Structure As an AAA+ ATPase, TRIP13 (and its PCH2 analog) forms homohexamers and interacts with ATP as an energy source. With respect to Hop1, PCH2 binds to and structurally changes Hop1, displacing the Hop1 from DNA. TRIP13/PCH2 interacts with ATP as a hydrolase, hydrolyzing phosphates to derive energy for conformational changes that can induce mechanical force on its substrate, Hop1 in the previous case. TRIP14/PCH2 is believed to have a single AAA+ ATPase domain. TRIP13/PCH2 also functions as a kinetochore protein that interacts with the silencing protein p31-Comet. Role in meiosis G2/prophase Meiosis in mammalian cells have a series of checkpoints and steps that need to be properly regulated. TRIP13/PCH2 has been implicated in these processes in budding yeast as well, particularly in the meiosis G2/prophase stage. Double stranded breaks during meiosis is a key part of this phase and is impacted by TRIP13. The homologous recombination that occurs following these breaks requires a protein complex to influence and structure appropriate chromosomal pairing. In a paper by San-Segundo et al., localization assays and induced mutations in PCH2 in budding yeast was shown to be required for the meiotic checkpoint to prevent chromosome segregation when the recombination or chromosome synapsis are defective. TRIP13, PCH2's analog, was also shown to be required for the formation of the synaptonemal complex – the complex that structures chromosomal pairings. Without TRIP13, meiocytes had pericentric synaptic forks, fewer crossovers, and altered distribution of chiasma (the contact point between homologous chromosomes. For this synaptonemal complex (SC) formation,