recommended for detection of Ser 637 phosphorylated UBF of mouse, rat and human origin by WB, IF and ELISA; also reactive with additional species, including canine, bovine and porcine
UBF Background Information 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 (1–3). UBF activity is regulated in a cell cycle-dependent manner by phosphorylation at serine residues near the
C terminus (3–5). Activation of UBF requires phosphorylation at multiple residues, including Ser 388, Ser 484 and Ser 637 (6,7). Phosphorylation of UBF at Serine 484 by G(1)-specific cyclin-dependent kinase (cdk)/cyclin complexes is necessary to activate rDNA transcription (7). After G(1), UBF is phosphorylated by cdk2/cyclin E and cdk2/cyclin A at Serine 388 (7). UBF phosphorylation induces transactivation of RNA polymerase I (5). Specifically, Serine 388 phosphorylation is required for the interaction between RNA polymerase I and UBF (7). The human UBF gene maps to the BRCA1 region of chromosome 17q21.3 and encodes a 764 amino acid protein (1,8). Alternative splicing yields two isoforms of UBF, which differ by 37 amino acids (2).
