DYNLT3 (dynein light chain Tctex-type 3) is a non-catalytic component of the cytoplasmic dynein 1 complex that mediates cargo-adapter binding and intracellular transport. Structurally, DYNLT3 directly binds the spindle checkpoint protein BUB3, linking dynein to the kinetochore complex 1. This interaction positions DYNLT3 as critical for mitotic progression: knockdown increases the mitotic index and impairs chromosome X 1, while depletion in oocytes causes kinetochore-microtubule detachment and blocks homologous chromosome X 2. DYNLT3 is also a component of dynein-2, which mediates retrograde intraflagellar transport 3. Pathologically, DYNLT3 functions as a tumor promoter in multiple cancer types. In breast cancer, elevated DYNLT3 expression promotes epithelial-to-mesenchymal transition (EMT) through increased N-cadherin and vimentin with decreased E-cadherin, driving proliferation, migration, and invasion 4. Conversely, in cervical cancer, DYNLT3 overexpression inhibits proliferation and suppresses Wnt/β-catenin signaling and EMT 5. In ovarian cancer, microRNA-1-3p suppresses DYNLT3 to reduce cell growth and metastasis 6. DYNLT3 expression correlates with age-associated breast cancer risk 7. ChrX deletions involving DYNLT3 occur in X-linked chrX granulomatous disease 8.