p-UBF Anticuerpo(Ser 388)-R: sc-21637-R

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Upstream binding factor (UBF) is a nucleolar transcription factor that is a member of the HMG-box DNA-binding protein family and is required for the expression of 18S, 5.8S and 28S ribosomal RNA . UBF activity is regulated in a cell cycle-dependent manner by phosphorylation at serine residues near the C terminus. Activation of UBF requires phosphorylation at multiple residues, including Ser 388, Ser 484 and Ser 637. Phosphorylation of UBF at Serine 484 by G-specific cyclin-dependent kinase (cdk)/cyclin complexes is necessary to activate rDNA transcription. After G, UBF is phosphorylated by cdk2/cyclin E and cdk2/cyclin A at Serine 388. UBF phosphorylation induces transactivation of RNA polymerase I . Specifically, Serine 388 phosphorylation is required for the interaction between RNA polymerase I and UBF. The human UBF gene maps to the BRCA1 region of chromosome 17q21.3 and encodes a 764 amino acid protein. Alternative splicing yields two isoforms of UBF, which differ by 37 amino acids.