TRAK2 is a mitochondrial trafficking adaptor that coordinates bidirectional motor transport along microtubules. Primary function: TRAK2 activates both kinesin-1 for anterograde (plus-end) transport and dynein for retrograde (minus-end) mitochondrial movement, forming an interdependent motor complex that enables integrated control of opposing motors 1. Mechanism: TRAK2 localizes to mitochondria via interaction with Miro GTPases and links cargo to kinesin and dynein-dynactin motors through conserved coiled-coil motifs 1. TRAK2 mRNA contains a 3'UTR regulatory motif that directs cell-size-dependent polarized localization, scaling mitochondrial distribution to match cell dimensions 2. Disease relevance: TRAK2 downregulation is associated with cancer progression—reduced TRAK2 expression promotes osteosarcoma cell proliferation, invasion, and migration via miR-487b targeting 3, while circSLC22A3-mediated TRAK2 upregulation suppresses esophageal cancer metastasis 4. In Alzheimer's disease, amyloid precursor protein and its fragments impair TRAK2 expression and mitochondrial-protein colocalization, contributing to mitochondrial transport defects and mitophagy failure 5. Clinical significance: TRAK2 represents a therapeutic target for cancer treatment and potential intervention point for neurodegenerative disease. Additionally, TRAK2 negatively regulates cholesterol efflux and HDL biogenesis through ABCA1 suppression, suggesting relevance to atherosclerosis prevention 6.