Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.3.5 (5'-nucleotidase)
 3,167 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Differences in cell morphology, concanavalin A-induced receptor redistributions, and the cooperativity of the inhibition of 5'-nucleotidase (AMPase) by concanavalin A (Con A) have been investigated in ascites sublines of the 13762 rat mammary adenocarcinoma cells treated with microfilament- and microtubule-perturbing drugs. By scanning electron microscopy MAT-C1 cells exhibit a highly irregular surface, covered with microvilli extending as branched structures from the cell body. MAT-A, MAT-B, and MAT-B1 cells have a more normal appearance, with unbranched microvilli, ruffles, ridges, and blebs associated closely with the cell body. MAT-C cells have an intermediate morphology. Treatment of MAT-A, MAT-B, or MAT-B1 cells with Con A causes rapid redistribution of Con A receptors. Both cytochalasins and colchicine cause alternations in the receptor redistributions. Receptors on MAT-C1 cells are highly resistant to redistribution, even in the presence of cytoskeletal perturbant drugs. The cooperativity of the inhibition of AMPase by Con A was investigated in MAT-A and MAT-C1 cells. Untreated cells exhibit no cooperativity. If either subline is treated with colchicine, cytochalasin B or D, or dibucaine, cooperativity is observed. Lumicolchicine has no effect. Theophylline or dibutyryl cyclic AMP prevents the effects of either colchicine or cytochalasin. The concentration required for half-maximal induction of cooperativity is 0.3--0.4 microM for both colchicine and cytochalasin D, which is in the appropriate range for specific microtubule and microfilament disruptions. The effectiveness of the cytochalasins (E greater than D greater than B) is consistent with their known effects on microfilaments. No direct correlation was observed between the induction of cooperativity and drug-induced changes in Con A receptor redistribution or cell morphology. The morphology of MAT-A cells is grossly altered by cytochalasins or dibucaine and somewhat less by colchicine. MAT-C1 cells exhibit more minor alterations in morphology as a result of these drug treatments. The results of this study indicate that the inhibition of AMPase, which is a Con A receptor, is a different process from the redistribution of the bulk of the Con A receptors, possibly short range membrane interactions rather than global effects on the cell.
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PMID:Effects of cytoskeletal perturbant drugs on ecto 5'-nucleotidase, a concanavalin A receptor. 23 Jan 91

The inhibition of the cell surface enzyme 5'-nucleotidase by concanavalin A is being studied as a model for understanding transmembrane modulation of cell surface functions. Nucleotidase of 13762 MAT-C1 ascites rat mammary adenocarcinoma cells is inhibited by concanavalin A in a noncooperative process. When cells are treated with the cytoplasmic effectors cytochalasins, colchicine, energy poisons, calcium plus ionophore or hypotonic buffers, the concanavalin A inhibition of the enzyme becomes cooperative. 5'-Nucleotidase of isolated MAT-C1 microvilli is also inhibited by concanavalin A in a noncooperative process; however, treatment of the microvilli with the same cytoplasmic effectors does not induce cooperativity. Since previous studies in several systems have suggested an association of nucleotidase with actin-containing microfilaments or the cell cytoskeleton, one explanation for the cooperativity changes is that they result from a change in the association of the enzyme with the cytoskeleton. However, Triton X-100 extractability of nucleotidase is the same for MAT-C1 cells exhibiting cooperative or noncooperative concanavalin A inhibition. Moreover, enzyme from cells exhibiting cooperative inhibition can be extracted into the zwitterionic detergent Zwittergent in a cooperative form, while enzyme exhibiting noncooperative behavior can be extracted into Zwittergent in a noncooperative form. Gel filtration and rate-zonal sucrose density gradient centrifugation showed little discernible size or sedimentation difference between enzyme samples exhibiting noncooperative and cooperative inhibition. These results indicate that changes in the cooperativity of the concanavalin A inhibition of nucleotidase are not a result of changes in the association of the enzyme with the cytoskeleton. These studies emphasize the caution which must be exercised in interpreting the effects of cytoskeletal perturbants on cell surface functions.
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PMID:Transmembrane modulation of the concanavalin A inhibition of 5'-nucleotidase is not due to a direct association of the enzyme with the cytoskeleton. 298 74