Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.5.4.4 (adenosine deaminase)
 5,136 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have previously demonstrated that a transcriptional arrest site exists in exon 1 of the human adenosine deaminase (ADA) gene and that this site may play a role in ADA gene expression (Z. Chen, M. L. Harless, D. A. Wright, and R. E. Kellems, Mol. Cell. Biol. 10:4555-4564, 1990). Sequences involved in this process are not known precisely. To further define the template requirements for transcriptional arrest within exon 1 of the human ADA gene, various ADA templates were constructed and their abilities to confer transcriptional arrest were determined following injection into Xenopus oocytes. The exon 1 transcriptional arrest signal functioned downstream of several RNA polymerase II promoters and an RNA polymerase III promoter, implying that the transcriptional arrest site in exon 1 of the ADA gene is promoter independent. We identified a 43-bp DNA fragment which functions as a transcriptional arrest signal. Additional studies showed that the transcriptional arrest site functioned only in the naturally occurring orientation. Therefore, we have identified a 43-bp DNA fragment which functions as a transcriptional arrest signal in an orientation-dependent and promoter-independent manner. On the basis of our findings, we hypothesize that tissue-specific expression of the ADA gene is governed by factors that function as antiterminators to promote transcriptional readthrough of the exon 1 transcriptional arrest site.
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PMID:Sequence requirements for transcriptional arrest in exon 1 of the human adenosine deaminase gene. 194 87

The relative rates of transcription of the human adenosine deaminase (ADA) gene were determined in isolated nuclei from T and B lymphoblasts and skin fibroblasts. ADA gene transcription occurs at higher rates in T cells than in B cells and fibroblasts. Relative steady state ADA mRNA levels were also determined for each cell line, and these values were found to correlate with relative rates of transcription of the gene. Therefore, the primary mechanism for control of expression of this ubiquitous enzyme is at the level of transcription. The ratios of ADA enzymatic activity to specific mRNA content were also compared between cell lines. The B lymphoblasts exhibited lower ratios than did the T lymphoblasts, suggesting that rates of protein degradation were several fold greater in B than in T lymphoblast cell lines. This finding is consistent with previous direct measurements of ADA protein turnover. Differential rates of protein turnover in B as compared to T cells provide a secondary mechanism for the regulation of ADA expression. In addition to transcription initiation being the major control mechanism of steady state ADA mRNA in all cell lines, first intron elongation pausing occurs in fibroblasts, and discrete regions of RNA polymerase II and RNA polymerase III antisense transcripts are observed in all cell lines studied.
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PMID:Cell type-specific transcriptional regulation of the human adenosine deaminase gene. 278 3

In 15-20% of children with severe combined immunodeficiency (SCID), the underlying defect is adenosine deaminase (ADA) deficiency. The goal of this study was to determine the precise molecular defect in a patient with ADA-deficient SCID whom we previously have shown to have a total absence of ADA mRNA and a structural alteration of the ADA gene. By detailed Southern analysis, we now have determined that the structural alteration is a deletion of approximately 3.3 kb, which included exon 1 and the promoter region of the ADA gene. DNA sequence analysis demonstrates that the deletion created a novel, complete Alu repeat by homologous recombination between two existing Alu repeats that flanked the deletion. The 26-bp recombination joint in the Alu sequence includes the 10-bp "B" sequence homologous to the RNA polymerase III promoter. This is the first example of homologous recombination involving the B sequence in Alu repeats. Similar recombination events have been identified involving Alu repeats in which the recombination joint was located between the A and B sequences of the polymerase III split promoter. The nonrandom location of these events suggests that these segments may be hot spots for recombination.
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PMID:Adenosine deaminase (ADA) deficiency due to deletion of the ADA gene promoter and first exon by homologous recombination between two Alu elements. 336 97