YB1

YB-1, or Y-box binding protein 1, is a ubiquitously expressed RNA- and DNA-binding protein encoded by the YBX1 gene in humans. It belongs to the cold shock protein family and contains a central cold shock domain flanked by N- and C-terminal regions that mediate nucleic acid interactions. The protein binds to Y-box elements in gene promoters and to RNA in the cytoplasm, enabling roles in transcriptional regulation and post-transcriptional control of mRNA translation and stability.

Functionally, YB-1 can act as a transcription factor or cofactor for growth- and stress-related genes. In RNA metabolism it influences translation initiation by interacting with 5' untranslated regions, initiation factors, and poly(A)-binding protein, often repressing or enhancing translation depending on context, especially under cellular stress.

Subcellular localization is primarily cytoplasmic, but YB-1 translocates to the nucleus in response to DNA damage, oxidative stress, or oncogenic signaling. Its activity is modulated by post-translational modifications, including phosphorylation by various kinases.

Clinically, elevated YB-1 levels and especially nuclear localization correlate with tumor progression, chemoresistance, and poorer prognosis in several cancers, making it a subject of biomarker and therapeutic-target research.

Evolutionarily conserved, YB-1 is found across vertebrates and participates in diverse cellular processes beyond cancer, including development and stress responses.