Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.26.9 (ribonuclease)
 6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The human gene encoding aquaporin-CD (AQP-CD) was isolated, and its structural organization was characterized. The gene appeared to exist as a single copy in the human genome and comprises four exons distributing over 5 kilobases. The size range of exons is 81-761 base pairs, and that for introns is approximately 3000 to approximately 250 base pairs. The exon-intron boundaries of human AQP-CD gene are identified at identical positions in other related genes, the human AQP-CHIP gene and the human major intrinsic protein gene. The major transcription initiation sites were identified to positions 93 and 94 base pairs upstream of the ATG initiation codon by primer extension and ribonuclease protection assay. The 5'-flanking region of the hAQP-CD gene was characterized by a TATA box, two GATA consensus sequences, an AP-1 site, an AP-2 site, three E-boxes, and a cyclic AMP-responsive element. These structural features will lead to a better understanding of the mechanisms of tissue-specific expression and the regulation by dehydration in AQP-CD gene and will also be of help in search for possible genetic disorders in human AQP-CD gene.
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PMID:Isolation of human aquaporin-CD gene. 752 28

Three members of the water channel (aquaporin) family are expressed in adult rat lung: CHIP28 (AQP-1), MIWC (AQP-4), and AQP-5. Because water channels may be important in the clearance of fluid from the newborn lung, the expression of water channels just before and after birth was investigated using the ribonuclease (RNAse) protection assay. RNA was isolated from lungs, brain, and heart of prenatal rats (fetal days F19, F20, and F21) and postnatal rats (days +1, +2, +5, +7, +21, and adult). Transcript expression was measured relative to a beta-actin control by quantitative densitometry. Whereas beta-actin mRNA expression was nearly constant over time, distinct expression patterns were observed for the three water channels. CHIP28 mRNA expression rose slowly from days F19 to +1, then strongly at day +2, and remained elevated over the first week. MIWC mRNA was weakly expressed prenatally, but strongly increased just after birth. AQP-5 mRNA increased slowly and monotonically between days F20 and +7. These patterns contrasted sharply with the developmental expression of CHIP28 in heart, which decreased over time, and MIWC in brain. Immunocytochemistry showed CHIP28 protein expression in capillary endothelia and MIWC in airway epithelia by day +1; quantitative immunoblot analysis showed increased CHIP28 protein expression over time. These findings are consistent with a role of lung water channels in perinatal fluid clearance; however, proof of physiologic significance will require functional measurements of air space-capillary water permeability.
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PMID:Sharp increase in rat lung water channel expression in the perinatal period. 891 74