Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0039483 (giant cell arteritis)
 3,204 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The expression of certain normal genes requires a specific ribosomal frameshift event because the mRNA has the coding information for one protein in two different reading frames. One of several possible mechanisms for this involves recognition of a nontriplet codon by a noncognate tRNA. The AGUC-decoding Escherichia coli tRNASer3 reads a GCA alanine codon to cause a -1 frameshift. Replacement of the anticodon of tRNAPhe with the anticodon of tRNASer3 allows the constructed tRNA to cause this frameshifting. By altering the anticodon loop nucleotides at positions 33-36 in the constructed tRNAPhe molecules, the tRNA was found to recognize a 2-base codon. Instead of the usual anticodon, positions 34-36, the nucleotides in positions 34 and 35 form essential base pairs with the first two positions of the alanine codon. The uridine in position 36 is also required but not for base pairing.
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PMID:tRNA anticodon replacement experiments show that ribosomal frameshifting can be caused by doublet decoding. 242 61

We have used the temperature-jump relaxation technique to determine the kinetic and thermodynamic parameters for the association between the following tRNAs pairs having complementary anticodons: tRNA(Ser) with tRNA(Gly), tRNA(Cys) with tRNA(Ala) and tRNA(Trp) with tRNA(Pro). The anticodon sequence of E. coli tRNA(Ser), GGA, is complementary to the U*CC anticodon of E. coli tRNA(Gly(2] (where U* is a still unknown modified uridine base) and A37 is not modified in none of these two tRNAs. E. coli tRNA(Ala) has a VGC anticodon (V is 5-oxyacetic acid uridine) while tRNA(Cys) has the complementary GCA anticodon with a modified adenine on the 3' side, namely 2-methylthio N6-isopentenyl adenine (mS2i6A37) in E. Coli tRNA(Cys) and N6-isopentenyl adenine (i6A37) in yeast tRNA(Cys). The brewer yeast tRNA(Trp) (anticodon CmCA) differs from the wild type E. coli tRNA(Trp) (anticodon CCA) in several positions of the nucleotide sequence. Nevertheless, in the anticodon loop, only two interesting differences are present: A37 is not modified while C34 at the first anticodon position is modified into a ribose 2'-O methyl derivative (Cm). The corresponding complementary tRNA is E.coli tRNA(Pro) with the VGG anticodon. Our results indicate a dominant effect of the nature and sequence of the anticodon bases and their nearest neighbor in the anticodon loop (particularly at position 37 on the 3' side); no detectable influence of modifications in the other tRNA stems has been detected. We found a strong stabilizing effect of the methylthio group on i6A37 as compared to isopentenyl modification of the same residue. We have not been able so far to assess the effect of isopentenyl modification alone in comparison to unmodified A37. The results obtained with the complex yeast tRNA(Trp)-E.coli tRNA(Pro) also suggest that a modification of C34 to Cm34 does not significantly increase the stability of tRNA(Trp) association with its complementary anticodon in tRNA(Pro). The observations are discussed in the light of inter- and intra-strand stacking interactions among the anticodon triplets and with the purine base adjacent to them, and of possible biological implications.
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PMID:Temperature jump relaxation studies on the interactions between transfer RNAs with complementary anticodons. The effect of modified bases adjacent to the anticodon triplet. 391 29

Three distinct genes encode an identical calmodulin protein in mammalian cells. In addition, multiple mRNA transcripts, with approximate sizes of 1.6 kb and 4.4 kb, are visualized on Northern blots hybridized to calmodulin-I cDNA probes. To elucidate the mechanism generating multiple calmodulin mRNAs, the complete sequence of the 4194 base human calmodulin-I mRNA was determined from cDNA clones and 3' rapid amplification of complementary ends (3' RACE). The 5' untranslated region of calmodulin-I mRNA contains a GC-rich domain containing multiple repeats of GGC interrupted by a GCA sequence, as well as a tandem repeat sequence of eight GCA triplets. The 3' untranslated region of calmodulin-I mRNA contains two canonical and one aberrant (ATTAAA) polyadenylation signal, consistent with the sizes of 1.6 kb and 4.4 kb mRNAs visualized on Northern blots, and a potential minor 4.2 kb mRNA detected by 3' RACE. Hybridization experiments using specific probes upstream and downstream of the polyadenylation signals demonstrated that alternate use of polyadenylation signals is the molecular mechanism for multiple calmodulin-I mRNA transcripts in human cells. Thirteen adenine rich elements with the motif AUUUA were detected in the 3' untranslated region. Three such motifs are embedded in regions that are conserved with the rat 3' untranslated region of calmodulin-I mRNA. One of these is surrounded by an adenine-uridine rich region that can form an 11-base pair stem structure. We propose that sequences in the 3' untranslated region of calmodulin-I mRNA may play a role in the regulation of calmodulin expression.
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PMID:Multiple mRNA species are generated by alternate polyadenylation from the human calmodulin-I gene. 759 66