Protein Domain : Retinoblastoma-associated protein, B-box IPR002719

Type	Domain
Description	This entry includes retinoblastoma-associated protein (RB, also known as pRb, RB, p1051), retinoblastoma-like protein 1 (RBL1, also known as p107) and retinoblastoma-like protein 2 (RBL2, also known as RB2 or p130). Members of this entry contain a conserved domain named the 'pocket' that interacts with the LXCXE motif found in viral proteins, such as SV40 large T antigen [ ]. This pocket consists of A- and B-boxes which are found at the C-terminal end of the protein. This entry represents the B-box, that is on C-terminal side of the A-box. The crystal structure of the RB pocket bound to a nine-residue E7 peptide containing the LxCxE motif, shared by other RB-binding viral and cellular proteins, shows that the LxCxE peptide binds a highly conserved groove on the B-box portion of the pocket; the A-box portion (see ) appears to be required for the stable folding of the B box. Also highly conserved is the extensive A-B interface, suggesting that it may be an additional protein-binding site. The A and B boxes each contain the cyclin-fold structural motif, with the LxCxE-binding site on the B-box cyclin fold being similar to a Cdk2-binding site of cyclin A and to a TBP-binding site of TFIIB [ , ].In humans, RB is a tumour suppressor linked to several major cancers [ ]. RB forms complexes with E2Fs and represses gene expression by recruiting chromatin remodeling factors, such as histone deacetylases (HDACs) to E2F-responsive promoters [, ]. Apart from E2Fs, RB also interacts with other transcription factors that govern cell differentiation [, ].RBL1 and RBL2 are the components of the DREAM complex, which represses cell cycle-dependent genes in quiescent cells and plays a role in the cell cycle-dependent activation of G2/M genes [ , ].
Short Name	RB_B