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)

The interaction of human recombinant interferon (rIFN) alpha 2 with its receptor on lymphoblastoid cells was studied using competitive displacement binding. The data were analysed with the LIGAND program, which tests their fit to one-site or multiple binding site models. The binding at 4 degrees and 37 degrees C fits a one-site model, with a similar KD for both IFN-sensitive and resistant cells. Binding at 37 degrees C to Daudi cells at high density fits artifactually a two-site model only when the receptor concentration is close to that of the KD. The binding of IFN to its receptor, therefore, follows a simple bimolecular interaction. Furthermore, IFN-sensitive and resistant cells internalize IFN at similar rates. We have examined whether IFN receptors are also internalized and whether they subsequently recycle to the cell surface. By measuring cell surface and total receptors, we have observed that after 2 h treatment with IFN total receptors remain constant whereas cell surface receptors decrease. After prolonged treatment with IFN, however, there is a loss of total receptors. By inactivating cell surface receptors with proteinase K, we have shown that a fraction of cell surface receptors becomes resistant to inactivation and is apparently internalized. Moreover, experiments which measure IFN receptors either during incubation in the presence of IFN or after IFN has been removed from the medium, show that receptors do not recycle to the cell surface after internalization. The addition of monensin, a drug which has been shown to inhibit receptor recycling, has no effect on the loss of IFN receptors.
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PMID:Single high affinity binding of interferon alpha 2 to receptors on human lymphoblastoid cells: internalization and inactivation of receptors. 315 92

Conditioned medium from a human myelomonocytic cell line THP-1 promoted the growth of a wide variety of cell types, i.e., human and mouse myeloid cells (HL-60, U937, K562, and M1), mouse T-cells (EL-4), human B cells (Daudi and Raji), mouse mastocytoma cells (IC-2), human melanoma cells (A375-C6), mouse transformed fibroblast cells (L929), human lung fibroblast cells (TIG-1), and mouse bone marrow fibroblast/stromal-like cells. The growth-promoting activity was acid-labile. The activity was resistant to 50 degrees C for 5 min but completely lost in 5 min at 70 degrees C. The activity was resistant to treatment with trypsin but sensitive to chymotrypsin alpha, Pronase E, and proteinase K, indicating the proteinous nature of this activity. The activity was lost by dithiothreitol and 2-mercaptoethanol. Molecular weight (M(r) 50,000-70,000) was estimated by gel filtration-high performance liquid chromatography. After the sequential anion exchange, hydrophobic, and hydroxylapatite high performance liquid chromatography, the partially purified factor exhibited the same target cell spectrum as the conditioned medium.
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PMID:Human myelomonocytic cell line THP-1 produces a novel growth-promoting factor with a wide target cell spectrum. 846 8

SYNOPSIS: Reports that elasmobranchs (sharks, skates, and rays) may have a low incidence of disease have stimulated interest in understanding the role of their immune system in this apparent resistance. Although research in this area may potentially translate into applications for human health, a basic understanding of the elasmobranch immune system components and how they function is essential. As in higher vertebrates, elasmobranch fishes possess thymus and spleen, but in the absence of bone marrow and lymph nodes, these fish have evolved unique lymphomyeloid tissues, namely epigonal and Leydig organs. As conditions for short-term culture of elasmobranch immune cells have become better understood, the opportunity to examine functional activity of cytokine-like factors derived from conditioned culture medium has resulted in the identification of growth inhibitory activity against a variety of tumor cell lines. Specifically, the medium enriched by short term culture of bonnethead shark (Sphyrna tiburo) epigonal cells (epigonal conditioned medium, ECM) has been shown to inhibit the growth of mammalian tumor cell lines, including fibrosarcoma (WEHI-164), melanoma (A375.S2), B-cell lymphoma (Daudi), T-cell leukemia (Jurkat), pancreatic cancer (PANC-1), ovarian cancer (NIH:OVCAR-3), and three breast carcinoma cell lines (MCF7, HCC38, Hs578T). Of the cell lines tested, WEHI-164, A375.S2, Daudi, and Jurkat cells were among the most sensitive to growth inhibitory activity of ECM whereas PANC-1 and NIH:OVCAR-3 cells were among the least sensitive. In addition, ECM demonstrated preferential growth inhibition of malignant cells in assays against two different malignant/non-malignant cell line pairs (HCC38/HCC38 BL and Hs 578T/Hs 578Bst). Separation of protein components of ECM using SDS-PAGE resulted in a very reproducible pattern of three major bands corresponding to molecular sizes of approximately 40-42 kD, 24 kD, and 17 kD. Activity is lost after heating at 75 degrees C for 30 min, and can be diminished by treatment with proteinase K and protease. Activity is not affected by treating with trypsin, DNase I or RNase A.
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PMID:Elasmobranch immune cells as a source of novel tumor cell inhibitors: Implications for public health. 1934 8