Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.1 (chymotrypsin)
 10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

CHIP is the archetypal member of the aquaporins, a widely expressed family of membrane water channels. The NH2- and COOH-terminal halves of CHIP are sequence-related, and hydropathy analysis predicted six membrane-spanning domains with five connecting loops (A-E). Here, we determined the membrane topology of CHIP expressed in Xenopus oocytes using biologically active recombinant channels. CHIP is glycosylated at Asn-42, indicating loop A is exofacial. An epitope from the coronavirus E1 glycoprotein was inserted into CHIP and localized to the outer or inner leaflet of the membrane by alpha-chymotrypsin digestion of intact oocytes or inside-out membrane vesicles. The E1 epitope at Thr-120 was protease-sensitive in intact oocytes, indicating that loop C is exofacial. The E1 epitope at Lys-6, Arg-162, or Lys-267 was protease-sensitive in inside-out membrane vesicles, confirming the cytoplasmic location of the NH2 and COOH termini and loop D. Insertions into loops B and E did not produce active water channels, but their cleavage patterns were consistent with inner (loop B) and outer (loop E) leaflet locations. This study indicates that the functional CHIP molecule is a unique structure with two internal repeats oriented 180 degrees to each other within the membrane.
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PMID:Membrane topology of aquaporin CHIP. Analysis of functional epitope-scanning mutants by vectorial proteolysis. 750 81

A general and simple implementation of simultaneous multiparametric sensing in a single microchip is presented by using a capillary-assembled microchip (CAs-CHIP) integrated with the plural different reagent-release capillaries (RRCs), acting as various biochemical sensors. A novel "drop-and-sip" technique of fluid handling is performed with a microliter droplet of a model sample solution containing proteases (trypsin, chymotrypsin, thrombin, elastase) and divalent cations (Ca2+, Zn2+, Mg2+) that passes through the microchannel with the aid of a micropipette as a vacuum pump, concurrently filling each RRC via capillary force. To avert the evaporation of the nanoliter sample volume in each capillary, PDMS oil is dropped on the outlet hole of the CAs-CHIP exploiting the capillary force that results in spontaneous sealing of all the RRCs. In addition, this high-speed sample introduction alleviates the possibility of protein adsorption and capillary cross-contamination, allowing a reliable and multianalyte determination of a sample containing many different proteases and divalent cations by using the fluorescence image analysis. Presented results suggested the possible application of this microchip in the field of drug discovery and systems biology.
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PMID:Integration of multianalyte sensing functions on a capillary-assembled microchip: simultaneous determination of ion concentrations and enzymatic activities by a "drop-and-sip" technique. 1726 15

Parkin suppression induces accumulation of beta-amyloid in mutant tau mice. We studied the effect of parkin suppression on behaviour and brain pathology in APP(swe) mutant mice. We produced double mutant mice with human mutated APP(swe)+partial (hemizygote) or total (homozygote) deletion of Park-2 gene. We studied the development, behaviour, brain histology, and biochemistry of 12- and 16-month-old animals in 6 groups of mice, with identical genetic background: wild-type (WT), APP(swe) overexpressing (APP), hemizygote and homozygote deletion of Park-2 (PK(+/-) and PK(-/-), respectively), and double mutants (APP/PK(+/-) and APP/PK(-/-)). APP mice have reduced weight gain, decreased motor activity, and reduced number of entrances and of arm alternation in the Y-maze, abnormalities which were partially or completely normalized in APP/PK(+/-) and APP/PK(-/-) mice. The double mutants had similar number of mutant human APP transgene copies than the APP and levels of 40 and 80 kDa proteins; but both of them, APP/PK(+/-) and APP/PK(-/-) mice, had less plaques in cortex and hippocampus than the APP mice. APP mutant mice had increased apoptosis, proapoptotic Bax/Bcl2 ratios, and gliosis, but these death-promoting factors were normalized in APP/PK(+/-) and APP/PK(-/-) mice. APP mutant mice had an increased number of tau immunoreactive neuritic plaques in the cerebral cortex as well as increased levels of total and phosphorylated tau protein, and these changes were partially normalized in APP/PK(+/-) heterozygotic and homozygotic APP/PK(-/-) mice. Compensatory protein-degrading systems such as HSP70, CHIP, and macroautophagy were increased in APP/PK(+/-) and APP/PK(-/-). Furthermore, the chymotrypsin- and trypsin-like proteasome activities, decreased in APP mice in comparison with WT, were normalized in the APP/PK(-/-) mice. We proposed that partial and total suppression of parkin triggers compensatory mechanisms, such as chaperone overexpression and increased autophagy, which improved the behavioural and cellular phenotype of APP(swe) mice.
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PMID:The effects of parkin suppression on the behaviour, amyloid processing, and cell survival in APP mutant transgenic mice. 1981 12