concanavalin-a has been researched along with lactacystin* in 2 studies
2 other study(ies) available for concanavalin-a and lactacystin
| Article | Year |
|---|---|
Expression of alternatively spliced CD45 isoforms by channel catfish clonal T and B cells is dependent on activation state of the cell and regulated by protein synthesis and degradation.
In mammals, expression of the three alternatively spliced exons of the tyrosine phosphatase CD45 is regulated by the developmental and activation state of the cell. In comparison, the channel catfish, Ictalurus punctatus, CD45 homolog contains 18 functional alternatively spliced exons. Since very little is known about CD45 regulation in ectothermic vertebrates, this study examines the regulation of catfish CD45 mRNA isoform expression in clonal T and B cells in response to stimulation. Results show that mitogenic stimulation using catfish serum or concanavalin A induced expression of mRNAs for small CD45 isoforms, and isoform message expression was growth curve dependent, i.e. cells in logarithmic phase express message for smaller CD45 isoforms, whereas stationary phase cells express message for longer CD45 isoforms. In addition, cells treated with the protein synthesis inhibitor cycloheximide expressed message for longer CD45 isoforms, and treatment with lactacystin, which blocks protein degradation, rescued smaller isoform message expression. Collectively these data suggested that expression of CD45 isoforms, in catfish, at least at the mRNA level, is "constitutively dynamic" and highly dependent on extracellular stimuli. Topics: Acetylcysteine; Alternative Splicing; Animals; B-Lymphocytes; Clone Cells; Concanavalin A; Cycloheximide; Feedback, Physiological; Gene Expression Profiling; Ictaluridae; Immunization; Leukocyte Common Antigens; Lymphocyte Activation; Protein Isoforms; T-Lymphocytes | 2010 |
Separation of cathepsin A-like enzyme and the proteasome: evidence that lactacystin/beta-lactone is not a specific inhibitor of the proteasome.
Previous studies have described a human platelet cathepsin A-like enzyme with a number of similarities to the "acidic" and "neutral" chymotrypsin-like activities of the proteasome. This includes its strong inhibition by the highly specific proteasome inhibitor Lactacystin/beta-lactone, suggesting that either the Cbz-Phe-Ala-hydrolyzing activity attributed to cathepsin A was due to the chymotrypsin-like activity of the proteasome or that lactacystin was not a specific inhibitor of the proteasome. In the present study we discard the first possibility on the basis of the following findings: (a) human platelet cathepsin A, unlike proteasome, binds to concanavalin A, and does not bind to Heparin-Sepharose at pH 7.4; (b) neither the chymotrypsin-like activity of the proteasome, nor proteasome antigens are detected in the cathepsin A preparation; (c) purified proteasome does not exhibit Cbz-Phe-Ala-hydrolyzing activity; (d) Z-lle-Glu-(Ot-Bu)Ala-leucinal (PSI), a compound that selectively inhibits the chymotrypsin-like activity of the proteasome at a concentration of 10 microM has no inhibitory effect on the carboxypeptidase activity of cathepsin A; (e) cathepsin A, free of the proteasome, is completely inhibited by micromolar concentrations of lactacystin/beta-lactone. It is therefore concluded that lactacystin/beta-lactone is not a specific inhibitor of the proteasome. Topics: Acetylcysteine; Animals; Blood Platelets; Cathepsin A; Cell Line, Tumor; Chromatography, Affinity; Concanavalin A; Cysteine Proteinase Inhibitors; Heparin; Humans; Mice; Proteasome Endopeptidase Complex; Proteasome Inhibitors | 2000 |