Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.64 (proteinase K)
 4,071 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It has been proposed that the estrogen receptor bears proteolytic activity responsible for its own transformation. This activity was inhibited by aprotinin. Incubation of transformed ER with aprotinin modified the proteolytic digestion of the hormone binding subunit by proteinase K. The smallest hormone-binding fragment of the ER, obtained by tryptic digestion, was still able to bind to aprotinin. These results suggest that aprotinin interacts with ER and the hormone-binding domain of ER is endowed with a specific aprotinin-binding site.
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PMID:An aprotinin binding site localized in the hormone binding domain of the estrogen receptor from calf uterus. 169 80

A new immunohistochemical method using a monoclonal estrogen receptor (ER) antibody and a progesterone receptor (PR) antibody has been performed to determine hormonal receptors on Bouin's liquid fixed and paraffin embedded tissue. This technique has been evaluated by comparison with conventional immunohistochemistry on frozen sections for 100 surgical biopsy specimens of breast carcinoma Erica (C) Prica (C); in 77 of these cases it was compared with enzyme immunoassay analyses (ER-EIA, PR-EIA). After a pretreatment by proteinase K for ER, the two specific monoclonal antibodies ER or PR were incubated overnight and revealed with a streptavidin biotin complex. The specific staining for ER and PR were exclusively located in the nuclei of cancer cells in both paraffin for ER and PR were exclusively located in the nuclei of cancer cells in both paraffin and frozen sections. The results on paraffin-embedded material were compared successively with ERICA (C) and ER-EIA and with PRICA (C) and PR-EIA. In 100 breast infiltrating carcinomas studied simultaneously on both paraffin and frozen sections, the concordance was 82% for ER and 85% for PR. In 77 breast carcinoma studied simultaneously on paraffin sections and EIA, the concordance was 74% for ER and 79.2% for PR. These results suggest that in the absence of frozen material, an immunohistochemical method on paraffin-embedded material can be used with a lower sensibility than on frozen sections. However, the detection of both ER and PR allows the identification of the hormondependent cases.
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PMID:[Human breast cancer embedded in paraffin, fixed in Bouin's fluid. Immunohistochemical analysis of estrogen and progesterone receptors]. 195 56

An inhibitory component that diminishes estrogen receptor (ER) binding to nuclei in vitro is present in cytosol prepared from calf uterus. The inhibitor is heat stable and resistant to enzymatic treatment with trypsin, chymotrypsin, proteinase K, deoxyribonuclease I, or ribonucleases A, T1, and U2. Results of chromatography on DEAE-cellulose and Sephadex G-150 indicate that the factor is a negatively charged macromolecule. Inhibitory activity is sensitive to sequential digestion with chondroitinase ABC, hyaluronidase, and heparinase. Approximately 70% of the inhibitory activity is destroyed by treatment with heparinase alone. Heparitinase destroys only 30% of this activity. Furthermore, the addition of pure hyaluronic acid or chondroitin sulfate to the ER-nuclei binding assay results in little inhibition, whereas addition of heparin inhibits 75% of receptor binding. Overall, these results indicate that glycosaminoglycans, present in bovine uterine cytosol, are capable of inhibiting ER-nuclei interactions. The most potent inhibitory glycosaminoglycan displays heparin-like characteristics.
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PMID:Characterization of a cytosolic inhibitor of calf estrogen receptor binding to nuclei. 330 79

Estrogen-regulated gene expression is dependent on interaction of the estrogen receptor (ER) with the estrogen response element (ERE). We assessed the ability of the ER to activate transcription of reporter plasmids containing either the consensus vitellogenin A2 ERE or the imperfect pS2, vitellogenin B1, or oxytocin (OT) ERE. The A2 ERE was the most potent activator of transcription. The OT ERE was significantly more effective in activating transcription than either the pS2 or B1 ERE. In deoxyribonuclease I (DNase I) footprinting experiments, MCF-7 proteins protected A2 and OT EREs more effectively than the pS2 and B1 EREs. Limited protease digestion of the A2, pS2, B1, or OT ERE-bound receptor with V8 protease or proteinase K produced distinct cleavage products demonstrating that individual ERE sequences induce specific changes in ER conformation. Receptor interaction domains of glucocorticoid receptor interacting protein 1 and steroid receptor coactivator 1 bound effectively to the A2, pS2, B1, and OT ERE-bound receptor and significantly stabilized the receptor-DNA interaction. Similar levels of the full-length p160 protein amplified in breast cancer 1 were recruited from HeLa nuclear extracts by the A2, pS2, B1, and OT ERE-bound receptors. In contrast, significantly less transcriptional intermediary factor 2 was recruited by the B1 ERE-bound receptor than by the A2 ERE-bound receptor. These studies suggest that allosteric modulation of ER conformation by individual ERE sequences influences the recruitment of specific coactivator proteins and leads to differential expression of genes containing divergent ERE sequences.
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PMID:Allosteric modulation of estrogen receptor conformation by different estrogen response elements. 1143 12

The preovulatory surge of estrogen up-regulates estrogen receptor-alpha (ER) gene expression in the uterus during the estrous/menstrual cycles of female mammals. Previously, we demonstrated that the 5-fold increase in ER mRNA levels in endometrium of ovariectomized ewes treated with a physiological dose of estradiol (E2) is entirely due to an increase in ER mRNA stability. Our current work confirms that the E2 effect is specific to ER mRNA. The sequence of ER mRNA, cloned from sheep endometrium, shows a high degree of conservation with those of other species, even in the 5'- and the very long 3'-untranslated regions. In a cell-free assay, ER mRNA demonstrates greater stability with endometrial extracts from E2-treated ewes compared with those from untreated ovariectomized ewes. The E2-enhanced stability of ER mRNA was ablated by prior treatment of the extracts with proteinase K, 70 C heat, and oxidizing and alkylating reagents, indicating that a protein is responsible for stabilization of the message. The 3'-untranslated region of ER mRNA contains discrete sequences required for E2-enhanced stability, four of which were identified by extensive deletion mutant analyses. Transfer of two of the four minimal E2-modulated stability sequences conferred E2-enhanced stability to a heterologous RNA. These minimal E2-modulated stability sequences contain a common 10-base, uridine-rich sequence that is predicted to reside in a loop structure. Throughout our studies, estrogen stabilization of ER mRNA in sheep endometrium resembled that of vitellogenin mRNA in frog liver, indicating conservation of this ancient mechanism for enhancing gene expression in response to estrogen.
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PMID:Estradiol stabilizes estrogen receptor messenger ribonucleic acid in sheep endometrium via discrete sequence elements in its 3'-untranslated region. 1255 62

Rabbit monoclonal (RM) antibodies appear to have higher affinity for antigens than mouse monoclonal (MM) antibodies. However, RM antibodies have not been used in veterinary diagnostic immunohistochemistry. The authors compared reactivities of RM and MM antibodies on formalin-fixed, paraffin-embedded canine tissues, targeting 11 different antigens: CD3, CD79a, calcitonin, calretinin, chromogranin A, COX-2, estrogen receptor, Ki67, progesterone receptor, synaptophysin, and vimentin. Paraffin-embedded tissue sections were processed by 1 of 2 antigen-retrieval methods: 1) proteinase K digestion or 2) steam heat in citrate buffer. An additional set of slides did not receive antigen retrieval. Immunostaining was performed using an automated stainer, and scores were assigned to the different dilutions and antigen-retrieval methods on the basis of staining intensity and number of positive cells. Steam heat was usually the best antigen-retrieval method. The optimal dilution for each antibody was that which resulted in the highest specific staining and the lowest nonspecific (background) staining. The RM or MM antibodies yielded a specific reaction for all antigens examined except calretinin. The RM and MM antibodies yielded a specific reaction for 4 antigens only: COX-2, Ki67, synaptophysin, and vimentin. Three antigens (CD3, chromogranin A, and progesterone receptor) were detected only with RM antibodies, whereas the other 3 (CD79a, calcitonin, estrogen receptor) were detected only with MM antibodies. The results of this study differed from those reported for human tissues by the manufacturers of the antibodies. These results emphasize that, regardless of manufacturers' recommendations, each antibody must be individually standardized and validated before routine use in canine tissues.
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PMID:Comparison of rabbit monoclonal and mouse monoclonal antibodies in immunohistochemistry in canine tissues. 1613 Sep 92