title: The hnRNP F protein: unique primary structure, nucleic acid-binding properties, and subcellular localization.
abstract: More than 20 different heterogeneous nuclear ribonucleoproteins (hnRNPs) are associated with pre-mRNAs in the nucleus of mammalian cells and these proteins appear to influence pre-mRNA processing and other aspects of mRNA metabolism and transport. The arrangement of hnRNP proteins on pre-mRNAs is likely to be unique for each RNA and may be determined by the different RNA-binding preferences of each of these proteins. hnRNP F (M(r) = 53 kD, pI = 6.1) and hnRNP H (M(r) = 56 kD, pI = 6.7-7.1) are abundant components of immunopurified hnRNP complexes and they have distinct nucleic acid binding properties. Unlike other hnRNP proteins which display a varying range of affinities for different ribonucleotidehomopolymers and ssDNA, hnRNP F and hnRNP H bind only to poly(rG) in vitro. hnRNP F and hnRNP H were purified from HeLa cells by poly(rG) affinity chromatography and oligonucleotides derived from peptide sequences were used to isolate a cDNA encoding hnRNP F. The predicted amino acid sequence of hnRNP F revealed a novel protein with three repeated domains related to the RNP consensus sequence RNA-binding domain. Monoclonal antibodies produced against bacterially expressed hnRNP F were specific for both hnRNP F and hnRNP H and recognized related proteins in divergent organisms, including in the yeast Saccharomyces cerevisiae. hnRNP F and hnRNP H are thus highly related immunologically and they share identical peptides. Interestingly, immunofluorescence microscopy revealed that hnRNP F and hnRNP H are concentrated in discrete regions of the nucleoplasm, in contrast to the general nucleoplasmic distribution of previously characterized hnRNP proteins. The unique RNA-binding properties, amino acid sequence and distinct intranuclear localization of hnRNP F and hnRNP H make them novel hnRNP proteins that are likely to be important for the processing of RNAs containing guanosine-rich sequences.
authors.affiliation: Howard Hughes Medical Institute, University of Pennsylvania School of Medicine, Philadelphia 19104-6148.
authors.forename: M J
authors.initials: MJ
authors.lastname: Matunis
authors.forename: J
authors.initials: J
authors.lastname: Xing
authors.forename: G
authors.initials: G
authors.lastname: Dreyfuss
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002417:Cattle; D002460:Cell Line; D002467:Cell Nucleus / Q000737:chemistry; D002846:Chromatography, Affinity; D016384:Consensus Sequence; D017124:Conserved Sequence; D018076:DNA, Complementary / Q000737:chemistry / Q000302:isolation & purification; D006367:HeLa Cells; D034541:Heterogeneous-Nuclear Ribonucleoprotein Group F-H; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D006801:Humans; D007668:Kidney; D008969:Molecular Sequence Data; D011068:Poly G / Q000378:metabolism; D012313:RNA / Q000378:metabolism*; D012322:RNA Precursors / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012261:Ribonucleoproteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification*; D013347:Subcellular Fractions / Q000737:chemistry*
chemical_list: D018076:DNA, Complementary; D034541:Heterogeneous-Nuclear Ribonucleoprotein Group F-H; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D012322:RNA Precursors; D012333:RNA, Messenger; D012261:Ribonucleoproteins; D011068:Poly G; D012313:RNA