The N-terminal K homology domain of the poly(rC)-binding protein is a major determinant for binding to the poliovirus 5'-untranslated region and acts as an inhibitor of viral translation

The poly(rC)-binding proteins (PCBP1 and PCBP2) are RNA-binding proteins whose RNA recognition motifs are composed of three K homology (KH) domains. These proteins are involved in both the stabilization and translational regulation of several cellular and viral RNAs. PCBP1 and PCBP2 specifically interact with both the 5'-element known as the cloverleaf structure and the large stem-loop IV RNA of the poliovirus 5'-untranslated region. We have found that the first KH domain of PCBP2 (KH1) specifically interacts with the viral RNAs, and together with viral protein 3CD, KH1 forms a high affinity ternary ribonucleoprotein complex with the cloverleaf RNA, resembling the full-length PCBP protein. Furthermore, KH1 acts as a dominant-negative mutant to inhibit translation from a poliovirus reporter gene in both Xenopus laevis oocytes and HeLa cell in vitro translation extracts.     

Identification of a CD20-, FcepsilonRIbeta-, and HTm4-related gene family: sixteen new MS4A family members expressed in human and mouse

CD20, high-affinity IgE receptor beta chain (FcepsilonRIbeta), and HTm4 are structurally related cell-surface proteins expressed by hematopoietic cells. In the current study, 16 novel human and mouse genes that encode new members of this nascent protein family were identified. All family members had at least four potential membrane-spanning domains, with N- and C-terminal cytoplasmic domains. This family was therefore named the membrane-spanning 4A gene family, with at least 12 subgroups (MS4A1 through MS4A12) currently representing at least 21 distinct human and mouse proteins. Each family member had unique patterns of expression among hematopoietic cells and nonlymphoid tissues. Four of the 6 human MS4A genes identified in this study mapped to chromosome 11q12-q13.1 along with CD20, FcepsilonRIbeta, and HTm4. Thus, like CD20 and FcepsilonRIbeta, the other MS4A family members are likely to be components of oligomeric cell surface complexes that serve diverse signal transduction functions.     

Chromosome mapping of nine tropomyosin-related sequences in mice

Tropomyosins are a group of actin-binding proteins expressed as different isoforms in muscle and non-muscle cells. Two tropomyosin loci have already been mapped in the mouse genome, on Chromosomes (Chrs) 6 and 9. By using a human cDNA fragment of tropomyosin non-muscle isoform (TPM3) gene that maps on human Chr 1q, and a mapping panel from a murine interspecific cross, we mapped nine distinct tropomyosin-related loci in the mouse genome, on seven different chromosomes: Chrs 3, 4, 6, 7, 14, 17, and X.     

Proteomics of bovine mitochondrial RNA-binding proteins: HES1/KNP-I is a new mitochondrial resident protein

Proteomic analysis of bovine mitochondrial proteins with affinity to polyAdenylate or polyUridylate was performed in an effort to identify novel RNA-binding mitochondrial proteins. We have used 2D gel electrophoresis and MALDI-QqTOF mass spectrometry to identify a total of 64 proteins, of which 51 have defined mitochondrial function including 6 known RNA-binding proteins. HES1/KNP-I from the polyA-binding fraction of mitochondrial Triton extract showed exclusive mitochondrial localization when expressed in GFP-tagged form. The HES1/KNP-I gene is on human chromosome 21q22.3 and may be involved in several disorders mapped to that region. Thus, HES1/KNP-I is a proven mitochondrial resident protein with apparent tight membrane association and tentative RNA-binding properties.     

PCBP1在基因表达过程中的功能和作用机理

Poly（C）-binding protein 1 （PCBP 1）是一种RNA结合蛋白,其蛋白质相对分子质量约为38000。PCBP1含三个KH（hnRNP K homology）结构域,这些结构域对其结合RNA有重要作用。PCBP1的功能主要是参与基因转录及转录后调节,如前体mRNA的剪切、mRNA稳定性、mRNA翻译过程的沉默或增强等。本文主要对PCBP1参与的信号通路以及与人类疾病的关系进行综述,试图阐明PCBP1的生物学功能和作用机理。     

Chromosomal location of murine and human IL-1 receptor genes.

The gene for the type I interleukin-1 (IL-1) receptor has been mapped in both mouse and human. In the human genome, a combination of segregation analysis of rodent-human hybrid cells and chromosomal in situ hybridization has placed the gene on the long arm of chromosome 2, at band 2q12. This is near the reported map position of the loci for IL-1 alpha and IL-1 beta (2q13----2q21). The murine gene has been mapped by analysis of restriction fragment length polymorphisms in interspecific backcrosses to the centromeric end of chromosome 1, in a region that is syntenic to a portion of human chromosome 2. The murine Il-1r1 gene has thus been separated from the IL-1 genes, which lie on murine chromosome 2.     

Dispersed family of human genes with sequence similarity to farnesyl pyrophosphate synthetase

Prenyltransferases are a group of enzymes involved in the biosynthesis of both sterol and nonsterol isoprene compounds. Somatic cell hybrid studies and in situ hybridization show that the human genome contains five distinct loci that hybridize to the cDNA for the enzyme farnesyl pyrophosphate synthetase (FPS), a prenyltransferase that catalyzes the synthesis of an intermediate common to both the sterol and the nonsterol branches of the isoprene biosynthetic pathway. The loci identified in this report may correspond to unique prenyltransferase genes related to FPS or to pseudogenes. The loci mapped have been identified as farnesyl pyrophosphate synthetase-"like"-1 (FPSL-1) on chromosome 1q24-31, FPSL-2 on chromosome 7, FPSL-3 on chromosome 14, FPSL-4 on chromosome 15q14-q21, and FPSL-5 on chromosome Xq21-22. Multiple copies of sequences similar to those of FPS are also present in both the mouse and the rat.     

Structure and RNA binding of the third KH domain of poly(C)-binding protein 1

Poly(C)-binding proteins (CPs) are important regulators of mRNA stability and translational regulation. They recognize C-rich RNA through their triple KH (hn RNP K homology) domain structures and are thought to carry out their function though direct protection of mRNA sites as well as through interactions with other RNA-binding proteins. We report the crystallographically derived structure of the third domain of alphaCP1 to 2.1 A resolution. alphaCP1-KH3 assumes a classical type I KH domain fold with a triple-stranded beta-sheet held against a three-helix cluster in a betaalphaalphabetabetaalpha configuration. Its binding affinity to an RNA sequence from the 3'-untranslated region (3'-UTR) of androgen receptor mRNA was determined using surface plasmon resonance, giving a K(d) of 4.37 microM, which is indicative of intermediate binding. A model of alphaCP1-KH3 with poly(C)-RNA was generated by homology to a recently reported RNA-bound KH domain structure and suggests the molecular basis for oligonucleotide binding and poly(C)-RNA specificity.     

Multipoint linkage analysis in X-linked ocular albinism of the Nettleship-Falls type

Summary The genes that encode the alpha 1 (VI) and alpha 2 (VI) collagen chains, designated COL6A1 and COL6A2, map to human chromosomal band 21q22.3. Using pulsed-field gel electrophoresis and somatic cell hybrids, we found that COL6A1 and COL6A2 form a gene cluster on the most distal part of chromosome 21. Furthermore, we detected several DNA polymorphisms (both restriction site and VNTRs) associated with these loci. These polymorphisms make the COL6A1 and COL6A2 genes among the most informative markers on human chromosome 21.     

Specific recognition of the C-rich strand of human telomeric DNA and the RNA template of human telomerase by the first KH domain of human poly(C)-binding protein-2

Poly(C)-binding proteins (PCBPs) constitute a family of nucleic acid-binding proteins that play important roles in a wide spectrum of regulatory mechanisms. The diverse functions of PCBPs are dependent on the ability of the PCBPs to recognize poly(C) sequences with high affinity and specificity. PCBPs contain three copies of KH (hnRNP K homology) domains, which are responsible for binding nucleic acids. We have determined the NMR structure of the first KH domain (KH1) from PCBP2. The PCBP2 KH1 domain adopts a structure with three alpha-helices packed against one side of a three-stranded antiparallel beta-sheet. Specific binding of PCBP2 KH1 to a number of poly(C) RNA and DNA sequences, including the C-rich strand of the human telomeric DNA repeat, the RNA template region of human telomerase, and regulatory recognition motifs in the poliovirus-1 5'-untranslated region, was established by monitoring chemical shift changes in protein (15)N-HSQC spectra. The nucleic acid binding groove was further mapped by chemical shift perturbation upon binding to a six-nucleotide human telomeric DNA. The binding groove is an alpha/beta platform formed by the juxtaposition of two alpha-helices, one beta-strand, and two flanking loops. Whereas there is a groove in common with all of the DNA and RNA binders with a hydrophobic floor accommodating a three-residue stretch of C residues, nuances in recognizing flanking residues are provided by hydrogen bonding partners in the KH domain. Specific interactions of PCBP2 KH1 with telomeric DNA and telomerase RNA suggest that PCBPs may participate in mechanisms involved in the regulation of telomere/telomerase functions.     

Conserved physical linkage of GnRH-R and RBM8 in the medaka and human genomes

Candidate genes for human type II gonadotropin-releasing hormone receptor (GnRH-RII) reside on two separate loci, 1q12-q21 and 14q21-23, yet neither locus generates functional GnRH-RII. Instead, their opposite DNA strands encode functional RNA-binding motif protein 8 (RBM8s), which is also encoded by another locus, 5q13-q14. To elucidate the mechanism through which such multiple human GnRH-RII/RBM8 loci arose, here we have defined an RBM8 locus in a comparative model species, the medaka Oryzias latipes. The medaka RBM8, which exists as a single copy gene, is linked to, but does not overlap with, GnRH-R2 on linkage group (LG) 16, demonstrating the ancient origin of the physical linkage between GnRH-R and RBM8. The medaka LG 16 contains orthologous segments to the human chromosome 1 and therefore the 1q12-q21 locus would be an originating human GnRH-RII/RBM8 segment. Furthermore, like the human RBM8s on 1q12-q21 and 5q13-q14 but not that on 14q21-q23, the medaka RBM8 is a multiexon gene, indicating that the 14q21-q23 and 5q13-q14 loci were generated by retrotransposition and segmental genomic duplication, respectively, of the originating 1q12-q21 locus.     

Structure of a construct of a human poly(C)-binding protein containing the first and second KH domains reveals insights into its regulatory mechanisms

Poly(C)-binding proteins (PCBPs) are important regulatory proteins that contain three KH (hnRNP K homology) domains. Binding poly(C) D/RNA sequences via KH domains is essential for multiple PCBP functions. To reveal the basis for PCBP-D/RNA interactions and function, we determined the structure of a construct containing the first two domains (KH1-KH2) of human PCBP2 by NMR. KH1 and KH2 form an intramolecular pseudodimer. The large hydrophobic dimerization surface of each KH domain is on the side opposite the D/RNA binding interface. Chemical shift mapping indicates both domains bind poly(C) DNA motifs without disrupting the KH1-KH2 interaction. Spectral comparison of KH1-KH2, KH3, and full-length PCBP2 constructs suggests that the KH1-KH2 pseudodimer forms, but KH3 does not interact with other parts of the protein. From NMR studies and modeling, we propose possible modes of cooperative binding tandem poly(C) motifs by the KH domains. D/RNA binding may induce pseudodimer dissociation or stabilize dissociated KH1 and KH2, making protein interaction surfaces available to PCBP-binding partners. This conformational change may represent a regulatory mechanism linking D/RNA binding to PCBP functions.     

The Neurological Mouse Mutations Jittery and Hesitant Are Allelic and Map to the Region of Mouse Chromosome 10 Homologous to 19p13.3

Jittery (ji) is a recessive mouse mutation on Chromosome 10 characterized by progressive ataxic gait, dystonic movements, spontaneus seizures, and death by dehydration/starvation before fertility. Recently, a viable neurological recessive mutation, hesitant, was discovered. It is characterized by hesitant, uncoordinated movements, exaggerated stepping of the hind limbs, and reduced fertility in males. In a complementation test and by genetic mapping we have shown here that hesitant and jittery are allelic. Using several large intersubspecific backcrosses and intercrosses we have genetically mappedjinear the markerAmhand microsatellite markersD10Mit7, D10Mit21,andD10Mit23.The linked region of mouse Chromosome 10 is homologous to human 19p13.3, to which several human ataxia loci have recently been mapped. By excluding genes that map to human 21q22.3 (Pfkl) and 12q23 (Nfyb), we conclude that jittery is not likely to be a genetic mouse model for human Unverricht–Lundborg progressive myoclonus epilepsy (EPM1) on 21q22.3 nor for spinocerebellar ataxia II (SCA2) on 12q22–q24. The closely linked markers presented here will facilitate positional cloning of thejigene.     

Chromosomal mapping of three human LAMMER protein-kinase-encoding genes

The eukaryotic LAMMER protein kinase family is encoded by at least three loci in the human genome, designated CLK1, 2, and 3. We have mapped these loci to 2q33, 1q21, and 15q24, respectively, by fluorescent in situ hybridization. Additionally, a CLK2 pseudo-gene has been located to 7p15–21. Received: 2 June 1998 / Accepted: 16 July 1998