Bcl9-2: Proteins and Enzymes

Bcl9-2 (B-cell lymphoma 9-like protein; also Bcl9L and B9L) is a 200-220 kDa transcriptional regulator that belongs to the Bcl9 family of proteins. It is expressed in multiple tissues, particularly breast, and serves to recruit Pygopus to the Wnt-pathway beta-catenin-TCF complex in the nucleus. Bcl9-2 and Bcl9 are considered evolutionary duplicates of Legless that perform the same task with different regulation. Human Bcl9-2 is 1499 amino acids (aa) in length. It contains two Pro-rich regions (aa 280-493 and 891-1378). There are four potential alternate start sites at Met879, Met1000, Met708 and Met472. The last two start sites are accompanied by a deletion of aa 1241-1286, and a 62 aa substitution for the C-terminal 167 aa, respectively. Over aa 38-206, human Bcl9-2 is 94% aa identical to mouse Bcl9-2. Bcl9-2 has been identified as a phosphoprotein in several human cancer cell lines and mouse liver.