MOLECULAR-CLONING AND CHARACTERIZATION OF A NOVEL RETINOBLASTOMA-BINDING PROTEIN

We describe the isolation and characterization of a novel cDNA encodin g a polypeptide that interacts in a yeast two-hybrid system as well as in mammalian cells with the retinoblastoma (RB) protein. This new pro tein, which we call Rim, consists of 897 amino acids, has two leucine zipper motifs, and has a LECEE sequence previously identified as an RE -binding domain. Rim also has an E1A/CtBP-binding motif and four putat ive nuclear localization signals. Rim mRNA is expressed ubiquitously a t low levels in all human adult tissues tested and at much higher leve ls in several tumor cell lines. The Rim gene (HG;MW-approved symbol RB BP8) is localized on human chromosome 18q11.2. (C) 1998 Academic Press