Biomaterial Database

Structure of the gene for rat nucleolar protein B23. 1990

J H Chang, and M O Olson

Department of Biochemistry, University of Mississippi Medical Center, Jackson 39216-4505.

Protein B23 is an abundant RNA-associated nucleolar phosphoprotein involved in the ribosome assembly process. Previous studies showed that two forms of the protein (B23.1 and B23.2) are generated from a single gene via alternative splicing of 3' exons at the mRNA level (Chang, J. H., and Olson, M. O. J. (1989) J. Biol. Chem. 264, 11732-11737). We now report the structure of the complete B23 gene which spans 11-kilobases of DNA and contains 12 exons coding for the 294 amino acid residues. B23.1 mRNA is encoded by exons 1-9, 11, and 12, whereas exons 1-10 code for the B23.2 mRNA. Each exon codes for a relatively short segment of the protein (2-40 amino acid residues). The exons, which are distributed unevenly over the length of the gene, are separated by introns varying in size between 122 base pairs and 2.2 kilobases. Southern blot analyses using a probe derived from the untranslated segment of exon 10 suggests that a single expressed gene is present in the rat genome. Additional genomic clones contained apparent processed pseudogenes for protein B23. Primer extension studies and comparison with a processed pseudogene reveal a probable transcription initiation site at position -96 from the first ATG. The 5' region of the gene contains several possible regulatory elements. Three GC boxes which are potential binding sites for transcription factor Sp1 were found, including one within the first intron. A segment of about 1500 base pairs in the 5' region is unusually rich in the dinucleotide CpG. Although no CCAAT box was found a well-defined TATA box is present at position -126. The latter feature suggests that the B23 gene has some properties of tissue-specific genes in addition to the predominant characteristics of housekeeping genes.

UI	MeSH Term	Description	Entries
D007438	Introns	Sequences of DNA in the genes that are located between the EXONS. They are transcribed along with the exons but are removed from the primary gene transcript by RNA SPLICING to leave mature RNA. Some introns code for separate genes.	Intervening Sequences,Sequences, Intervening,Intervening Sequence,Intron,Sequence, Intervening
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D009687	Nuclear Proteins	Proteins found in the nucleus of a cell. Do not confuse with NUCLEOPROTEINS which are proteins conjugated with nucleic acids, that are not necessarily present in the nucleus.	Nucleolar Protein,Nucleolar Proteins,Nuclear Protein,Protein, Nuclear,Protein, Nucleolar,Proteins, Nuclear,Proteins, Nucleolar
D009841	Oligonucleotides	Polymers made up of a few (2-20) nucleotides. In molecular genetics, they refer to a short sequence synthesized to match a region where a mutation is known to occur, and then used as a probe (OLIGONUCLEOTIDE PROBES). (Dorland, 28th ed)	Oligonucleotide
D011544	Pseudogenes	Genes bearing close resemblance to known genes at different loci, but rendered non-functional by additions or deletions in structure that prevent normal transcription or translation. When lacking introns and containing a poly-A segment near the downstream end (as a result of reverse copying from processed nuclear RNA into double-stranded DNA), they are called processed genes.	Genes, Processed,beta-Tubulin Pseudogene,Gene, Processed,Processed Gene,Processed Genes,Pseudogene,Pseudogene, beta-Tubulin,Pseudogenes, beta-Tubulin,beta Tubulin Pseudogene,beta-Tubulin Pseudogenes
D003001	Cloning, Molecular	The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.	Molecular Cloning
D005091	Exons	The parts of a transcript of a split GENE remaining after the INTRONS are removed. They are spliced together to become a MESSENGER RNA or other functional RNA.	Mini-Exon,Exon,Mini Exon,Mini-Exons
D005796	Genes	A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms.	Cistron,Gene,Genetic Materials,Cistrons,Genetic Material,Material, Genetic,Materials, Genetic
D000090243	Nucleophosmin	Predominantly localized in the CELL NUCLEOLUS, involved in diverse cellular processes such as ribosome biogenesis, cytoplasmic-nuclear trafficking, centrosome duplication, and regulation of p53.	NO38 Protein,Nucleolar Phosphoprotein B23,Nucleolar Protein B23,Nucleophosmid,Numatrin,Phosphoprotein B23, Nucleolus,Protein B23,B23, Nucleolar Phosphoprotein,B23, Nucleolar Protein,B23, Nucleolus Phosphoprotein,B23, Protein,Nucleolus Phosphoprotein B23,Phosphoprotein B23, Nucleolar,Protein B23, Nucleolar,Protein, NO38
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein