Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P20020 (adenosine triphosphatase)
 3,299 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Intestinal epithelial cells contain calcium-binding proteins and Ca2+-transporting adenosine triphosphatase (Ca2+-ATPase), which play important roles in intestinal Ca transport. However, the factors that affect the expression of these transepithelial Ca-transporting proteins in dairy cattle are unknown. In this study, a semi-quantitative reverse transcription polymerase chain reaction was used to determine the expression of the mRNAs for intestinal Ca-binding protein calbindin-D9k (CaBP9k), two isoforms of plasma membrane Ca2+-ATPase (PMCA1 and PMCA4), and vitamin D receptor (VDR) in duodenal tissue samples from 20 non-lactating, non-pregnant Holstein dairy cattle (0.4-135.9 months old). The correlations between the expressions of transepithelial Ca-transporting proteins, the ages of the cattle, and the presence of several plasma components were evaluated. The duodenal CaBP9k mRNA content had a significant negative correlation with age and positive correlations with plasma inorganic phosphorus (iP) and 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) concentrations. The PMCA1 mRNA content was negatively correlated with the plasma Ca concentration. The duodenal PMCA4 mRNA content was correlated negatively with the plasma iP. The VDR mRNA content had a positive correlation with the plasma magnesium concentration.
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PMID:The expression of genes for transepithelial calcium-transporting proteins in the bovine duodenum. 1649 Jul 22

Epithelial calcium transport occurs by paracellular and transcellular mechanisms. Transcellular transport in intestinal and renal epithelia involves several transport proteins, including transient receptor potential vanilloid member 5 (TRPV5), member 6 (TRPV6), calbindin D9k (CB9), calbindin D28k (CB28), sodium calcium exchanger 1 (NCX1), plasma membrane calcium ATPase 1 (PMCA1), and the vitamin D receptor (VDR). We are interested in the horse because of its unique calcium physiology (high blood calcium, high intestinal calcium absorption, high renal excretion of calcium, low vitamin D concentrations), and because horses often have dysregulated calcium balance with various diseases. We cloned the mRNA for equine TRPV5, TRPV6, CB9, CB28, NCX1, PMCA1, and VDR, performed comparative mRNA and protein sequence analysis, and quantified their mRNA expression in the kidney and gastrointestinal tract. Sequence homology for the mRNAs and proteins was high among mammals (>75%), with fish having the lowest homology (<75%). TRPV5, TRPV6, and CB9 expression was higher in the duodenum and proximal jejunum and followed a similar expression pattern. CB28 expression was greatest in the kidney. PMCA1 and NCX1 expression was similar throughout the intestine, but in the kidney PMCA1 expression was higher. Based on our findings, the proximal small intestine is the main site for transcellular calcium transport, with TRPV6 and CB9 serving as the main transport proteins. In the kidney, TRPV6, CB28, and PMCA1 are likely more important. The low VDR expression in the equine small intestine and kidney relative to the large intestine, together with the reported high intestinal absorption and renal excretion of calcium, and low vitamin D concentrations suggests that epithelial calcium transport in horses is not as dependent on vitamin D as in other species.
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PMID:Cloning, comparative sequence analysis and mRNA expression of calcium-transporting genes in horses. 2022 85