Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0019204 (hepatocellular carcinoma)
 71,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have determined the sequence of cDNA for the human histidyl-tRNA synthetase (HRS) in a hepatoma cell line and confirmed it in fetal myoblast and fibroblast cell lines. The newly determined sequence differs in 48 places, including insertions and deletions, from a previously published sequence. By sequence specific probing and by direct sequencing, we have established that only the newly determined sequence is present in genomic DNA and we have sequenced 500 hundred bases upstream of the translation start site. The predicted amino acid sequence now clearly demonstrates all three motifs recognized in class 2 aminoacyl-tRNA synthetases. Alignment of E. coli, yeast, and when available, mammalian predicted amino acid sequences for three of the four members of the class 2a subgroup (his, pro, ser, and thr) shows strong preservation of amino acid specific signature regions proximal to motif 2 and proximal to motif 3. These probably represent the active site binding regions for the proximal acceptor stem and for the amino acid. The first two exons of human HRS contain a 32 amino acid helical motif, first described in human QRS, a class 1 synthetase, which is found also in a yeast RNA polymerase, a rabbit termination factor, and both bovine and human WRS, suggesting that it may be an RNA binding motif.
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PMID:Human histidyl-tRNA synthetase: recognition of amino acid signature regions in class 2a aminoacyl-tRNA synthetases. 154 69

The tRNA content and aminoacyl-tRNA synthetases of regenerating liver in the phase of rapid growth were compared with those of livers from both intact and sham-operated rats. At 48 h after hepatectomy, the amount of active tRNA (called 'total acceptor capacity') is significantly higher in regenerating liver than in control livers, owing to a general, possibly not uniform, increase in the various tRNA families, which suggests that it may contribute to the increased protein synthesis and to decreased protein degradation as well. The activities of most, but not of all, aminoacyl-tRNA synthetases in cell sap of regenerating liver tend to be greater than normal. Increased activity of histidyl-tRNA synthetase fits in with the possibility that the mechanisms that control the rate of protein degradation through aminoacylation of tRNAHis in cultured cells [Scornik (1983) J. Biol. Chem. 258, 882-886] also operate in the liver and play a role in regeneration. Sedimentation analysis of cell sap in sucrose density gradients shows a shift of prolyl-tRNA synthetase activity toward the high-Mr form in regenerating liver. This change might be related to the positive protein balance and to growth in vivo, since it is also observed in the anaplastic Yoshida ascites hepatoma AH 130.
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PMID:Effects of liver regeneration on tRNA contents and aminoacyl-tRNA synthetase activities and sedimentation patterns. 379 68