Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Infantile-onset glycogen storage disease type II, or Pompe disease, results from a genetic deficiency of the lysosomal enzyme acid alpha glucosidase (GAA). Sequencing of the cDNA from a cell line (GM 244) derived from a patient with Pompe disease demonstrated a T953-to-C transition that predicted a methionine-to-threonine substitution at codon 318. The basepair substitution resulted in loss of restriction-endonuclease sites for NcoI and StyI. Analysis of genomic DNA revealed both a normal and an abnormal NcoI fragment, indicating that the patient was a genetic compound. NcoI and StyI digestion of cDNA, amplified by PCR from reverse-transcribed RNA, demonstrated that greater than 95% of the GAA mRNA in GM 244 was derived from the allele carrying the missense mutation. The missense mutation was uncommon, since it was not detected in 37 additional GAA-deficient chromosomes, as determined by digestion of genomic DNA with NcoI and hybridization. The amino acid substitution predicts a new potential site for N-linked glycosylation, as well as major changes in secondary structure of the protein. We could confirm that the mutation was responsible for the enzyme deficiency by demonstrating that a hybrid minigene containing the mutation did not express GAA enzyme activity after transient gene expression. We have therefore now provided the first identification of a single-basepair missense mutation in a patient with Pompe disease and furthermore have demonstrated that the patient is a genetic compound with the second allele barely expressing mRNA.
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PMID:Identification of a missense mutation in one allele of a patient with Pompe disease, and use of endonuclease digestion of PCR-amplified RNA to demonstrate lack of mRNA expression from the second allele. 165 92

The importance of the role of acid alpha-glucosidase in the lysosomal degradation of glycogen has been emphasized because the deficiency of this enzyme in glycogenosis type II causes glycogen accumulation in lysosomes. Three clinical variants are distinguished. The infantile type has its onset shortly after birth and is known as generalized glycogen storage disease. The adult variant manifests itself mostly after the second decade of life and is characterized by progressive skeletal muscle weakness. The other is childhood type which is usually fatal by the second decade of life. Many biochemical reports of acid alpha-glucosidase have been published. Martiniuk et al reported the cDNA and amino acid sequence of human acid alpha-glucosidase. In prior studies, they reported that the lysosomal acid alpha-glucosidase was polymorphic with three alleles. The rarer allele GAA2 allozyme had a lower affinity for glycogen and starch. We also reported the enzyme heterogeneity in its affinity to Sephacryl S-200 gel. Whereby the enzyme separated into two fractions, S1 and S2. Each fraction contained 76 kDa and 67 kDa components on SDS/PAGE. The spleen enzyme consisted mainly of S1 fraction, containing only a 76 kDa component. In previous extensive studies, different mutations of Pompe's disease have been inferred from alterations in biochemical parameters. More recently Martiniuk et al, Hoefsloot et al and Van der Ploeg et al reported the analysis of cDNA and mRNA. These studies have revealed an absence or abnormal size of mRNA in large numbers of patients and altered restriction endonuclease fragments in a few patients.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Pompe's disease--acid alpha-glucosidase deficiency--a review]. 841 9

We cloned and partially characterized a human endonuclease (Xib) which shows sequence homologies to pancreatic DNase I but an enzymatic activity closer to DNase II. We report on the structural differences found between Xib and other recently cloned human DNases. Fluores cence microscopy analysis of transiently transfected cells with Xib::pEGFP constructs indicate that the protein is located in the cytoplasm and possibly anchored to a membrane, as deduced from a hydrophobic amino acid stretch present at the C-terminal end. Xib is overexpressed in muscle and cardiac tissues and is alternately spliced in several normal and neoplastic cells. In situ hybridization studies using human cardiac and muscle biopsies indicate accumulation of Xib transcript in the vacuoles of muscle cells from patients affected by vacuolar myopathy as acid maltase deficiency; however, no point mutations were detected in their DNA.
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PMID:Molecular characterization of a novel endonuclease (Xib) and possible involvement in lysosomal glycogen storage disorders. 1656 3