CTPS2 (CTP synthase 2) catalyzes ATP-dependent amination of UTP to produce CTP, a critical precursor for DNA, RNA, and phospholipid synthesis 1. As a rate-limiting enzyme in pyrimidine nucleotide biosynthesis, CTPS2 functions both as an independent enzyme and through direct interaction with its homolog CTPS1, forming homotetramers and large intracellular filament structures called cytoophidia 2. When associated with CTPS2, CTPS1 activity is modulated and becomes more sensitive to product feedback inhibition 2. CTPS2 regulates its enzymatic activity through dynamic polymerization into filaments that switch between active and inactive conformations in response to substrate and product levels, enabling highly cooperative regulation 1. While CTPS1 is essential for embryonic development and highly proliferative tissues, CTPS2 plays a complementary role outside hematopoietic systems 3. In cancer contexts, CTPS2 expression correlates with chemotherapy response: low CTPS2 expression confers 5-fluorouracil resistance in colorectal cancer, whereas EBV-transformed B cells require both CTPS1 and CTPS2 for optimal proliferation 45. These findings position CTPS2 as a potential therapeutic target in malignancies where pyrimidine metabolism is dysregulated.