Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.1 (RNase)
 16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pregnant rats were loaded with L-phenylalanine, and the distributions of [14C]leucine and [14C]urea into fetal plasma and tissues were examined. Uptake of [14C]leucine into the supernatant and protein fractions of fetal plasma and tissues was low in the rats loaded with phenylalanine. In contrast, [14C]urea was distributed identically in both groups, indicating that maternal hyperphenylalaninemia did not affect blood flow across the placenta. Administration of phenylalanine and p-chlorophenylalanine produced amino acid imbalance in fetal tissues. Along with these changes, polysomes of the affected fetal heart and brain disaggregated without changes in the ribonuclease activity. These results indicate that high phenylalanine levels in maternal plasma disturb the active transport of amino acids across the placenta, causing an amino acid imbalance and disaggregation of polysomes in fetal heart and brain. These changes may contribute to the congenital heart disease and mental retardation of maternal phenylketonuria.
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PMID:Effects of phenylalanine loading on protein synthesis in the fetal heart and brain of rat: an experimental approach to maternal phenylketonuria. 294 18

Phenylalanine hydroxylase (PAH) is the key enzyme in phenylalanine metabolism. PAH deficiency results in hyperphenylalaninemia, leading to severe mental retardation in the classical form of the disease, phenylketonuria (PKU). Previously the expression of PAH could only unambiguously be demonstrated in human liver, whereas in rodents PAH expression has been established in kidney and liver. Reports concerning PAH activity in other human or rodent tissues were severely questioned by subsequent investigations such that they did not gain general recognition. Conducting Northern blot analyses, we detected the PAH transcript in RNA isolated from human liver, kidney, pancreas, and brain. PAH gene expression in human kidney was subsequently investigated by RNase protection assay analyses, RNA in situ hybridization, immunohistochemistry, enzyme assay, and cDNA isolation. These experiments allowed the conclusive verification of a functional PAH enzyme in human kidney. The primary structure of the kidney transcript corresponded to the structure of the liver transcript. Human kidney PAH may play a significant role in phenylalanine homeostasis of the organism, as impaired phenylalanine hydroxylation has been observed in renal failure and differences in the regulation of the kidney versus the liver enzyme have been indicated. These results provide new aspects to research into the basis for the heterogeneity of hyperphenylalaninemia phenotypes and establish that the expression of the human PAH gene is not limited to the liver.
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PMID:Human phenylalanine hydroxylase gene expression in kidney and other nonhepatic tissues. 1044 41