Exportin-T

Exportin-T (XPOT) is a nuclear export receptor that mediates the transport of aminoacylated tRNAs from the nucleus to the cytoplasm (UniProt: O43592). The protein binds tRNA and the GTPase Ran-GTP to form a trimeric complex that docks at the nuclear pore complex; release of cargo occurs upon Ran-GTP hydrolysis in the cytoplasm, allowing the receptor to return to the nucleus for additional transport cycles. This mechanism underlies the directional control of nucleocytoplasmic tRNA trafficking.

XPOT functions as a core component of the tRNA export pathway, which is essential for protein synthesis and cellular homeostasis (UniProt: O43592). No pathway-level disease associations are noted in the UniProt record.

XPOT is upregulated in Alzheimer's disease brain tissue, with a mean log2 fold-change of 0.52 relative to age-matched controls, detected across two subcellular fractions in a quantitative proteomics study of post-mortem AD brain (Chaparral AD proteomics). This elevation may reflect altered tRNA homeostasis or compensatory changes in nucleocytoplasmic transport during AD neurodegeneration, though the functional significance remains to be determined.