MED25 is a subunit of the Mediator complex, a conserved transcriptional coactivator that bridges gene-specific regulatory proteins to RNA polymerase II machinery 1. As a component of the Mediator complex, MED25 functions as a scaffold for preinitiation complex assembly and is recruited to gene promoters through direct interactions with transcription factors, including retinoic acid receptors 2. MED25 contains an activator interaction domain (ACID) that serves as a docking site for transcriptional regulators, demonstrating conformational flexibility in binding diverse activators 3. Mutations in MED25 cause Basel-Vanagaite-Smirin-Yosef syndrome and Charcot-Marie-Tooth disease type 2B2, highlighting its essential role in neurological function 1. MED25 has been identified as a target for viral interference: respiratory syncytial virus NS1 protein binds MED25 ACID through dual interaction sites, potentially blocking access of host transcription factors and suppressing antiviral gene expression 34. Similarly, enterovirus 71 shares an epitope with MED25, suggesting cross-reactivity that may trigger autoimmune-mediated neurological complications 5. Increased MED25 peptide intensity has been detected in Alzheimer's disease plasma 6, though the functional significance requires clarification.