Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C1519176 (PSA)
 5,490 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Puromycin-sensitive alanyl aminopeptidase (PSA, EC 3.4.11.14) is a member of the ubiquitous aminopeptidase family, which cleaves N-terminal amino acids from proteins. PSA is suggested to function as a trimming protease in the MHC class I pathway, which is activated in brains of Alzheimer disease (AD). We examined the immunohistochemical localization of PSA in brains of AD and control cases using a rabbit anti-PSA. In the control cases, the antiserum revealed staining in a few glial cells and blood vessels. In AD brain, however, intensely stained cells were found richly in the cerebral cortex. Double immunofluorescence studies confirmed that PSA-positive cells were reactive microglia. Such PSA-positive reactive microglia tended to locate in and around senile plaques and were sometimes observed to associate with neurons containing neurofibillary tangles. The present result indicates that reactive microglia express PSA-immunoreactive molecules, probably in association with the pathological conditions of AD.
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PMID:Demonstration of puromycin-sensitive alanyl aminopeptidase in Alzheimer disease brain. 1293 12

Puromycin sensitive aminopeptidase (PSA or NPEPPS) is a M1 class aminopeptidase is selectively inhibited by the natural product puromycin, an aminonucleoside antibiotic produced by the bacterium Streptomyces alboniger. The molecular basis for this selective inhibition has not been understood well. Here, we report the basis for selectivity of puromycin using biochemical, structural and molecular modeling tools on four different M1 family enzymes including human PSA. Except for PSA, the other three enzymes were not inhibited. Instead, the peptide bond in the puromycin is hydrolyzed to O-methyl-L-tyrosine (OMT) and puromycin aminonucleoside (PAN). Neither of the hydrolyzed products, individually or together inhibit any of the four enzymes. Crystal structure of ePepN using crystals that are incubated with puromycin contained the hydrolyzed products instead of intact puromycin. On the other hand, intact puromycin molecule was observed in the crystal structure of the inactive mutant ePepN (E298A)-puromycin complex. Surprisingly, puromycin does not enter the active site of the mutant enzyme but binds near the entrance. Comparison of puromycin binding region in ePepN mutant enzyme and molecular modeling studies suggest that PSA might be inhibited by similar mode of binding there by blocking the entrance of the active site.
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PMID:Puromycin, a selective inhibitor of PSA acts as a substrate for other M1 family aminopeptidases: Biochemical and structural basis. 3304 97