title: Identification of the factors that interact with NCBP, an 80 kDa nuclear cap binding protein.
abstract: It has been shown that the monomethylated cap structure plays important roles in pre-mRNA splicing and nuclear export of RNA. As a candidate for the factor involved in these nuclear events we have previously purified an 80 kDa nuclear cap binding protein (NCBP) from a HeLa cell nuclear extract and isolated its full-length cDNA. In this report, in order to obtain a clue to the cellular functions of NCBP, we attempted to identify a factor(s) that interacts with NCBP. Using the yeast two-hybrid system we isolated three clones from a HeLa cell cDNA library. We designated the proteins encoded by these clones NIPs (NCBP interacting proteins). NIP1 and NIP2 have an RNP consensus-type RNA binding domain, whereas NIP3 contains a unique domain of Arg-Glu or Lys-Glu dipeptide repeats. We also show that NCBP requires NIP1 for binding to the cap structure. Possible roles of NIPs in cap-dependent nuclear processes are discussed.
mesh_terms: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D018900:Dinucleotide Repeats / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D039502:Nuclear Cap-Binding Protein Complex; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D039381:RNA Cap-Binding Proteins; D012315:RNA Caps / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000378:metabolism; D017422:Sequence Analysis, DNA
chemical_list: C096212:NCBP2 protein, human; D039502:Nuclear Cap-Binding Protein Complex; D009687:Nuclear Proteins; D039381:RNA Cap-Binding Proteins; D012315:RNA Caps; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins