Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: EC:3.1.27.1 (
RNase
)
16,360
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
The physiologic substrates of cytotoxic T lymphocyte granule-associated serine esterases (referred to hereafter as proteases or "granzymes"), and the role of these enzymes in cell-mediated activity remain unclear. We have developed an assay for possible ligands of the trypsin-like dimeric serine protease
granzyme A
based on Western immunoblotting techniques. This protein-binding assay demonstrates the selective binding of
granzyme A
to several proteins present in the target cell P815. The binding specificity is preserved when enzyme binding is performed in the presence of excess competing proteins, including such cationic species as lysozyme and
RNase
. Enzyme binding is inhibited, however, by heat or detergent inactivation of
granzyme A
. Subcellular fractionation of target cells shows that the nuclear fraction contains most
granzyme A
binding reactivity, which is recovered in the nuclear salt wash fraction. A protein with Mr = 100,000 and two closely migrating proteins with Mr = 35,000 and 38,000 are the predominant reactive moieties, and the N-terminal sequence of the 100-kDa protein confirmed that this protein was murine nucleolin. Incubation of
granzyme A
with nucleolin generates a discrete proteolytic cleavage product of Mr = 88,000. Since nucleolin is known to shuttle between nucleus and cytoplasm, the interaction of
granzyme A
and nucleolin may be important in the process of apoptosis which accompanies cytotoxic T lymphocyte-mediated lysis of target cells.
...
PMID:Granzyme A binding to target cell proteins. Granzyme A binds to and cleaves nucleolin in vitro. 186 Aug 69
Splenic B cells from BALB/c mice bearing mammary adenocarcinomas are capable of performing Ab-dependent cellular cytotoxicity. Effector-target conjugation after 18 h results in minimal cytoplasmic damage, whereas extensive nuclear disintegration is observed. To determine whether splenic B cells from tumor-bearing mice can effect direct cytotoxicity against tumor cells, L929 and WEHI 164 cells were used as targets. B lymphocytes from tumor-bearing mice, but not from normal animals, were capable of lysing these two types of tumor cells. However, only a low level of cytotoxicity could be detected when the nontumorigenic 3T3 cells were used as targets. To elucidate the mechanism of cytotoxicity of these killer B cells,
RNase
protection assays were performed using perforin,
granzyme A
, TNF-alpha, and lymphotoxin probes. No perforin,
granzyme A
, or lymphotoxin RNA could be detected in purified preparations of B cells from normal and tumor-bearing mice. B cells from normal mice did not have TNF-alpha RNA. In contrast, B cells from tumor bearers expressed TNF-alpha RNA. TNF-alpha could be detected in supernatants from both unstimulated and stimulated tumor bearers' splenic B cells, as measured by ELISA, and its lytic activity was neutralized by anti-TNF-alpha Ab. Western blots revealed the presence of TNF-alpha on the surface of the killer B cells. Paraformaldehyde-fixed B cells from tumor-bearing mice but not from normal animals were able to lyse TNF-alpha-sensitive tumor targets. This cytotoxicity was neutralized by anti-TNF-alpha Ab. These results suggest that TNF-alpha in soluble and membrane-bound forms may be involved in the mechanism of cytotoxicity exerted by B cells from tumor-bearing mice.
...
PMID:Soluble and membrane-bound TNF-alpha are involved in the cytotoxic activity of B cells from tumor-bearing mice against tumor targets. 814 19
