Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0162871 (abdominal aortic aneurysm)
 8,664 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The 15,697-nucleotide sequence of Paracentrotus lividus mitochondrial DNA is reported. This genome codes for 2 rRNAs, 22 tRNAs, and 12 mRNAs which specify 13 subunits of the mitochondrial inner membrane respiratory complexes. The gene arrangement differs from that of other animal species. The two ribosomal genes 16 S and 12 S are separated by a stretch of about 3.3 kilobase pairs which contains the ND1 and ND2 genes and a cluster of 15 tRNA genes. The ND4L coding sequence is not contained in the ND4 mRNA but has its own mRNA which maps between the tRNA(Arg) and the Co II genes. The main noncoding region, located in the tRNA gene cluster, is only 132 nucleotides long, but contains sequences homologous to the mammalian displacement loop. Other short noncoding sequences are interspersed in the genome: they contain a conserved AT consensus which probably has a role in transcription or RNA processing. As regards the mitochondrial genetic code, the codons AGA and AGG specify serine and are recognized by a tRNA with a GCU anticodon, whereas AUA and AAA code for isoleucine and asparagine rather than for methionine and lysine. Except for ND4L which starts with AUC and ATPase 8 which starts with GUG, AUG is used as the initiation codon. In 11 out of 13 cases the genes terminate with the canonical stop codons UAA or UAG. These observations suggest that during invertebrate evolution each lineage developed its own mechanism of mitochondrial DNA replication and transcription and of RNA processing and translation.
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PMID:The complete nucleotide sequence, gene organization, and genetic code of the mitochondrial genome of Paracentrotus lividus. 254 76

The 15,650 base-pair mitochondrial genome of the sea urchin Strongylocentrotus purpuratus has been cloned and sequenced. It exhibits a novel organization that suggests the primacy of post-transcriptional gene regulation. The same 13 polypeptides, two rRNAs and 22 tRNAs are encoded as in other animal mitochondrial DNAs, but are organized with extreme economy; non-coding information between genes is almost completely absent, some stop codons are generated post-transcriptionally and tRNA sequences are interspersed between only a minority of other structural genes. The genome uses a variant genetic code, in which AAA specifies asparagine, ATA isoleucine, TGA tryptophan and AGN serine, and has an unusual pattern of codon bias. The order of genes shows several differences from that of vertebrates. The genes for the large (16 S) ribosomal RNA and for NADH dehydrogenase subunit 4L (ND4L) are in different positions, located respectively between those encoding ND2 and cytochrome oxidase subunit I (COI) and between COI and COII. This organization is conserved amongst at least four regular echinoids diverging by some 225 million years. Most tRNA genes are also in different positions. The only long unassigned sequence in the genome (121 base-pairs) is located within a cluster of 15 tRNA genes. It contains elements resembling some of those found in the displacement (D) loop of vertebrate mtDNAs, notably polypurine/polypyrimidine tracts that may play a role in regulating transcription and the initiation of replication. The separation of the ribosomal RNA genes from each other and from the putative control region imposes special demands on the transcription of the genome.
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PMID:Nucleotide sequence and gene organization of sea urchin mitochondrial DNA. 317 15