Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.23.5 (cathepsin D)
 4,130 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Extracellular matrix vesicles, which have been shown to be associated with initial calcification of cartilage, were isolated, characterized, and studied with 45calcium isotope to determine whether they could form mineral in vitro. It was found that the isolated matrix vesicles contain a phosphatase, active at neutral pH, which has a very wide specificity and will hydrolyze a variety of nucleotide triphosphates, diphosphates, monophosphates, and other phosphate-containing substrate and metabolites. Acid phosphatase, beta-glucuronidase, and cathepsin D were found to be in the cell fractions, in lysosomes; these enzymes are not present in matrix vesicles and this is additional evidence for the difference between matrix vesicles and lysosomes. Matrix vesicles were found to take up 45Ca even in the presence of low levels of Ca and P1 and also to facilitate precipitation of hydroxylapatite when incubated under physiological conditions in the presence of ATP and other phosphate-containing substrates. Systematic electron probe analysis of a septum of epiphyseal cartilage indicates that matrix vesicles gradually accumulate calcium and then phosphorus and thus facilitate the advance of the calcification front. Adjoinging nonvesicular matrix in the hypertrophic zone, cell cytoplasm, and cell processes had very low levels of calcium and phosphorus in a region where matrix vesicles showed high levels of these elements. New concepts are put forward that take accounts of these findings which provide a better understanding of the sequence of mineralization in growth cartilage.
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PMID:Analysis of matrix vesicles and their role in the calcification of epiphyseal cartilage. 124 46

Protein synthesis and degradation and net uptake and release of amino acids and minerals were examined in the perfused hemicorpus of bilaterally nephrectomized and sham-operated control rats. Animals were studied 30 h after surgery. In comparison with controls, uremic rats had greater urea N appearance (net urea generation) and lower plasma and muscle concentrations of most amino acids. Muscle protein synthesis was not altered, but protein degradation was greater in uremic versus sham rats. There was greater net release of phenylalanine, tyrosine, alanine, total nonessential amino acids, total amino acids, potassium, and phosphorus from the perfused hemicorpus of uremic rats and greater release of citrulline from sham rats. ATP, creatine phosphate, cAMP, and activities of cathepsin B1, cathepsin D, and alkaline protease were not different in muscles of the uremic versus sham rats. Thus, in acutely uremic rats there is increased protein wasting in the hemicorpus due to enhanced protein degradation. The enhanced protein degradation does not appear to be due to increased muscle cathepsin B1, cathepsin D, or alkaline protease activities.
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PMID:Protein and amino acid metabolism in posterior hemicorpus of acutely uremic rats. 630 4

Protein synthesis and degradation and net uptake and release of amino acids and minerals were investigated in the perfused hemicorpus of acutely uremic and control Sprague-Dawley rats. Rats underwent bilateral nephrectomy or sham surgery and were studied 30 hr after surgery. The uremic rats displayed greater urea N appearance (net urea generation), lower plasma and muscle concentrations of most amino acids, and increased muscle protein degradation as compared to control rats. Muscle protein synthesis was slightly but not significantly decreased in the uremic animals. There was greater net release of phenylalanine, tyrosine, alanine, total nonessential amino acids, total amino acids, potassium and phosphorus from the perfused hemicorpus of uremic rats and greater release of citrulline from sham rats. Muscle ATP, creatine phosphate, cyclic-AMP, and activities of cathepsin B1, cathepsin D, and alkaline protease were not different in the uremic and sham rats. These data provide evidence that acutely uremic rats sustain increased muscle protein wasting which is due to enhanced protein degradation. The increased protein degradation does not appear to be due to enhanced activities of muscle cathepsin B1, cathepsin D or alkaline protease.
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PMID:Enhanced muscle protein degradation and amino acid release from the hemicorpus of acutely uremic rats. 636 19

Protein synthesis and degradation and net uptake and release of amino acids and minerals were investigated in the perfused hemicorpus of acutely uremic and sham-operated control Sprague-Dawley rats. Rats underwent bilateral nephrectomy or sham surgery and were studied 30 hours after surgery. The uremic rats displayed greater urea nitrogen appearance (net urea generation), lower plasma and muscle intracellular concentrations of most amino acids, and increased protein degradation in the hemicorpus as compared with control animals. Muscle protein synthesis was slightly but not significantly decreased in the uremic animals as compared with controls. There was greater net release of phenylalanine, tyrosine, alanine, total nonessential amino acids, total amino acids, potassium, and phosphorus from the perfused hemicorpus of uremic rats and greater release of citrulline from sham rats. Muscle ATP, creatine phosphate, and cyclic AMP, and muscle cathepsin B1, cathepsin D, and alkaline protease activities were not different in the uremic and control rats. These data provide evidence that acutely uremic rats have increased muscle protein wasting which is due to enhanced protein degradation. The cause of the increased muscle protein degradation is unknown.
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PMID:Effect of acute uremia on protein degradation and amino acid release in the rat hemicorpus. 658 68