1,721,039 research outputs found
POSSIBLE IDENTITY OF TRANSCRIPTION AND TRANSLATION SIGNALS IN EARLY VITAL SYSTEMS
No full textThe distribution of codons was analysed in three classes of eukaryote proteins having widely different evolutionary rates: 78 histones, 40 tubulins, and seven fibrinogens. In this set of genes, (i) it was confirmed that codons which are components of known transcription signals, like ATA, are used infrequently when a synonym is available, particularly in the more constrained proteins, and (ii) it was observed that the three codons which have an iso-accepting transfer with anticodon UAA, UAG or UGA are also suppressed. Then, the distribution of UAA, UAG and UGA trimers was studied in 498 tDNAs and 198 rDNAs. It was found that these trimers are weakly but significantly suppressed in tDNAs and to a lesser extent in rDNAs. It was advanced that the present suppression of ATA, which codes for Methionine in several mitochondria, and of the TAA, TAG and TGA trimers in tDNAs, might be an indication that at the very early stages of the evolution of translation and transcription the signals for initiation and termination were shared by the two processes
A SET OF ALU-FREE FREQUENT DECAMERS FROM MAMMALIAN GENOMES ENRICHED IN TRANSCRIPTION FACTOR SIGNALS
No full textWe have recently reported that the statistical analysis of the frequency distribution of short oligonucleotides within mammalian and viral genomes allows the production of sets of DNA sequences enriched in signals for transcription factors. Such statistical approaches could facilitate the identification of new promoter regions playing a role in the transcriptional regulation of gene expression. In the case of mammalian oligonucleotides, we found that the published set of frequent decamers enriched in transcriptional motifs is not suitable for studies on genes of Homo sapiens and evolutionarily related genomes, because it contains decameric sequences belonging to genomic repeats. We report here that most of the decameric sequences of DNA repeats belong to Alu repeats. Accordingly, we produced a subset of Alu-free frequent decamers. In addition, we eliminated from the subset of Alu-free frequent decamers those that are frequently present within other common human repeats, including (GT)n, (AT)n, (CA)n, (ATT)n, (CAA)n and (GTT)n. The Alu-free (repeats-free) subset of frequent mammalian decamers is enriched in signals for transcription factors and allows the identification of putative signals in genes, such as those coding for plasminogen activator, adenosine deaminase and p53, that contain a large number of Alu-like repeats interspersed within our genomic sequences. The newly generated compilation of frequent decamers described here might be used to locate genomic regions playing functional roles in the expression of genes of Homo sapiens and related primate
Expression of a novel human sialidase encoded by the NEU2 gene
No full textSialidases (EC 3.2.1.18) are a group of glycohydrolytic
enzymes, widely distributed in nature, that
cleave sialic acid residues from the oligosaccharide
components of glycoconjugates. All of the sialidase enzymes
thus far characterized share an Asp block, repeated
three to five times in the primary structure,
and an F/YRIP sequence motif that is part of the active
site. Using a sequence homology-based approach, we
have identified a novel human gene, named NEU2,
mapping to chromosome 2q37. The nucleotide sequence
analysis of the gene has shown that it contains
only one intron of about 1.25 kb, and the longest open
reading frame encodes a protein of 380 amino acids,
with a two-Asp block consensus, and the YRIP sequence.
In the putative promoter sequence there are a
classical TATAA box and four E boxes, which are consensus
binding sites for muscle-specific transcription
factors. Northern blot analysis revealed expression of
the NEU2 transcript only in skeletal muscle
Cytogenetic and oxidative damage induced in human lymphocytes by platinum, rhodium and palladium compounds
No full textClinical validity of the elbow flexion test for the diagnosis of ulnar nerve compression at the cubital tunnel
No full textCytokinesis-block micronucleus assay in primary human liver fibroblasts exposed to griseofulvin and mitomycin C
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