Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.1 (protein kinase)
 81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The yeast VPS15 gene encodes a novel protein kinase homolog that is required for the sorting of soluble hydrolases to the yeast vacuole. In this study, we extend our previous mutational analysis of the VPS15 gene and show that alterations of specific Gps15p residues, that are highly conserved among all protein kinase molecules, result in the biological inactivation of Vps15p. Furthermore, we demonstrate here that short C-terminal deletions of Vps15p result in a temperature-conditional defect in vacuolar protein sorting. Immediately following the temperature shift, soluble vacuolar hydrolases, such as carboxypeptidase Y and proteinase A, accumulate as Golgi-modified precursors within a saturable intracellular compartment distinct from the vacuole. This vacuolar protein sorting block is efficiently reversed when mutant cells are shifted back to the permissive temperature; the accumulated precursors are rapidly processed to their mature forms indicating that they have been delivered to the vacuole. This rapid and efficient reversal suggests that the accumulated vacuolar protein precursors were present within a normal transport intermediate in the vacuolar protein sorting pathway. In addition, this protein delivery block shows specificity for soluble vacuolar enzymes as the membrane protein, alkaline phosphatase, is efficiently delivered to the vacuole at the non-permissive temperature. Interestingly, the C-terminal Vps15p truncations are not phosphorylated in vivo suggesting that the phosphorylation of Vps15p may be critical for its biological activity at elevated temperatures. The rapid onset and high degree of specificity of the vacuolar protein delivery block in these mutants suggests that the primary role of Vps15p is to regulate the sorting of soluble hydrolases to the yeast vacuolar compartment.
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PMID:A genetic and structural analysis of the yeast Vps15 protein kinase: evidence for a direct role of Vps15p in vacuolar protein delivery. 175 16

At present, the exact mechanism of the pathogenic effect of anti-PR-3 antibodies remains unknown. Interaction of anti-neutrophil cytoplasmic antibodies (ANCAs) with human umbilical vein endothelial cells (HUVECs) may play a key role. Recently we were able to show that ANCAs recognize their target antigen, PR-3, translocated into the membrane of HUVECs. The objective of this study was to investigate regulation, i.e. signal transduction pathways, of PR-3 expression in endothelial cells. HUVECs were isolated according to the method of Jaffe et al. and cultured under standard conditions. A cyto-enzyme-linked immunosorbent assay (ELISA) with unfixed cells was performed. Membrane-expressed PR-3 was detected by affinity-purified and monoclonal anti-PR-3 Ab. Tumour necrosis factor alpha (TNF-alpha)-induced membrane expression of PR-3 could be blocked with the RNA synthesis inhibitor actinomycin D, the protein kinase C (PKC) and proteinase A (PKA) inhibitor staurosporine, the specific PKA inhibitor calphostin C, the c-AMP-dependent PKA inhibitor KT5720 and the tyrosine kinase inhibitor genistein in a dose-dependent manner. The effect of calphostin C was the most significant. In addition, the effect of phorbol 12-myristate 13-acetate (PMA), a mediator of intracellular second messengers, was investigated. In our study, pretreatment of cells with PMA for 48 h led to a down-regulation of PR-3 expression. This effect, however, could be overridden by TNF-alpha stimulation, i.e. TNF-alpha-induced membrane expression of PR-3 was resistant to down-regulation of PKC. In conclusion, our data suggest that translocation of PR-3 in HUVECs is an active process depending on protein synthesis. PR-3 expression by HUVECs may involve a PKC reactive to cytokines such as TNF-alpha which induces PR-3 expression at a transcriptional level.
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PMID:Signal transduction pathways of membrane expression of proteinase 3 (PR-3) in human endothelial cells. 939 84