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Results for “Plant Lectins”

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At least 19 recordsLinked to original sources
PubMed1975

Interaction of plant lectins with purified human lymphocyte populations: binding characteristics and kinetics of proliferation.

With six purified plant lectins as probes of cell surface structure, human T, B, and Null lymphocytes have been examined for cell surface differences. The results of binding experiments with radioiodinated lectins indicate that these three lymphocyte populations, although functionally different, bind equivalent amounts of E- and L-PHA, lentil PHA, Con A, RCA-I, and WGA. Since these lectins are capable of binding to at least four different cell surface oligosaccharides, these data indicate that human T, B, and Null lymphocytes do not differ with respect to surface content of these carbohydrate structures. In addition, all six lectins were investigated for their ability to stimulate DNA synthesis in these human lymphocyte populations. Four of these lectins (E- and L-PHA, lentil PHA, and Con A) were mitogenic for human lymphocytes, whereas RCA-I and WGA failed to stimulate significant DNA synthesis in any lymphocyte population. When incubated with the mitogenic lectins, both B and Null cells displayed a delayed peak of DNA synthesis in comparison to T cells. Thus, despite virtually identical binding characteristics, the lectin-induced mitogenic response exhibited by B and Null cells was markedly different kinetically from that of T cells.

Adsorption↗
PubMed1977

Immunological studies of Aging. III. Cytokinetic basis for the impaired response of lymphocytes from aged humans to plant lectins.

The basis for the age-associated defect in the response of lymphocytes to plant lectins has been studied. Using three independent assays we have shown that the number of mitogen-responsive cells is markedly reduced in lymphocyte preparations from old persons. In addition, studies using colchicine bloock and thymidine pulse techniques have revealed a failure of mitogen-responsive cells from old persons to expand into a proliferating pool of lymphocytes as is observed when lymphocytes from young persons are cultured with phytohemagglutinin. Thus, the impaired response of lymphocytes from old persons to mitogens is attributable to a reduced number of mitogen responsive cells and their failure to undergo clonal expansion.

Adult↗
PubMed1977

[Tissue antagonist of interferon : murine substance similar to plant lectins].

A tissue antagonist of interferon (TAI) extracted from mouse costal cartilage contains a substance which has many properties characteristic of plant lectins. After binding to the cell membrane receptors, it agglutines normal and transformed murine cells. In interferon treated cells, it restores virus sensitivity probably through a modification in the distribution of membrane bound cellular antigens.

Agglutination Tests↗
PubMed1975

Effects of local anesthetics on membrane properties. II. Enhancement of the susceptibility of mammalian cells to agglutination by plant lectins.

Treatment of untransformed mouse and hamster cells with the tertiary amine local anesthetics dibucaine, tetracaine and procaine increases their susceptibility to agglutination by low doses of the plant lectin concanavalin A. Agglutination of anesthetic-treated untransformed cells by low doses of concanavalin A is accompanied by redistribution of concanavalin A receptors on the cell surface to form patches, similar to that occurring in spontaneous agglutination of virus-transformed cells by concanavalin A. Immunofluorescence and freeze-fracture electronmicroscopic observations indicate that local anesthetics per se do not induce this redistribution of concanavalin A receptors but modify the plasma membrane so that receptor redistribution is facilitated on binding of concanavalin A to the cell surface. Fluorescence polarization measurements on the rotational freedom of the membrane-associated probe, diphenylhexatriene, indicate that local anesthetics produce a small increase in the fluidity of membrane lipids. Spontaneous agglutination of transformed cells by low doses of concanavalin A is inhibited by colchicine and vinblastine but these alkaloids have no effect on concanavalin A agglutination of anesthetic-treated cells. Evidence is presented which suggests that local anesthetics may impair membrane peripheral proteins sensitive to colchicine (microtubules) and cytochalasin-B (microfilaments). Combined treatment of untransformed 3T3 cells with colchicine and cytochalasin B mimics the effect of local anesthetics in enhancing susceptibility to agglutination by low doses of concanavalin A. A hypothesis is presented on the respective roles of colchicine-sensitive and cytochalasin B-sensitive peripheral membrane proteins in controlling the topographical distribution of lectin receptors on the cell surface.

Agglutination↗
PubMed1978

Use of common plant lectins for isolation and characterization of constitutive and developmentally regulated cell surface associated glycoproteins of Dictyostelium discoideum.

Glycoproteins as a class of molecules have been implicated as serving crucial roles in cell recognition events. Using 3 common plant lectins, we have isolated and identified a number of cell surface associated glycoproteins. The appearance of at least 5 of these proteins is under developmental regulation.

Chromatography, Affinity↗
PubMed1975

Lack of correlation between growth characteristics, agglutinability by plant lectins and the malignant phenotype.

Wheat germ agglutinin and Concanavalin A were found to agglutinate a variety of normal hamster cells as well as a number of lines of transformed or tumor cells. The normal cells included preparations from embryos and neonatal organs, and the spontaneous line, BHK-21 C13. In order to explore more fully the situation in regard to the BHK cells, three sublines were isolated and studied. A "flat revertant" selected by FUdR treatment grew to diminished saturation density and failed to produce colonies in soft agar in contrast to the parent line, which did. Yet, it was only minimally less tumorigenic and less agglutinable than the parent line. Lines derived from one and four consecutive in vivo tumor passages showed increased tumorigenicity and growth in soft agar when compared to the parent line. Although the first passage line showed increased saturation density, the saturation density of the fourth passage line was similar to or less than that of the parent cells. Agglutinability of these lines was not significantly increased. These results indicate that, in contrast to widely accepted beliefs, tumorigenicity may correlate poorly with growth characteristics and agglutination by plant lectins.

Agglutination↗
PubMed1979

Inhibition of human neuroblastoma DNA polymerase activities by plant lectins and toxins.

The effects of concanavalin A and ricin (RCAII, Mr 65,000) on [3H]thymidine incorporation into human neuroblastoma IMR-32 DNA showed reduction of total DNA synthesis to 50% and 70% of control, respectively. Two DNA polymerase (DNA nucleotidyltransferase, EC 2.7.7.7.) activities (alpha and beta) involved in the biosynthesis in vitro of DNA were separated by sucrose density gradient centrifugation from IMR-32 cell homogenate. The DNA polymerase alpha activity was also purified by selective precipitation with polyethylene glycol (Mr 6000) followed by agarose-concanavalin A column chromatography. The activities of both DNA polymerases were examined at various concentrations of mutagenic and nonmutagenic plant agglutinins and the toxin ricin. Concanavalin A and ricin specifically inhibited DNA polymerase alpha activity (activity reduced to 19% and 10%, respectively), whereas DNA polymerase beta activity was inhibited (reduced to 16%) by red kidney bean agglutinin (PHA-P).

Cell Line↗
PubMed1977

Complementation between mutants of CHO cells resistant to a variety of plant lectins.

Chinese hamster cell mutants resistant to the lectins PHA, WGA, RIC, LCA, and CON A were previously grouped into 8--10 distinct phenotypes on the basis of their unique patterns of lectin resistance and lectin-binding properties. All but one of these classes of lectin-resistant (LecR) mutants behave recessively in somatic cell hybrids. One ricin-resistant class (RicRII) behaves dominantly. Tests for complementation, by measuring the lectin-resistant properties of appropriate hybrids, show that seven distinct complimentation groups can be delineated among the phenotypically recessive mutants.

Cell Line↗
PubMed1979

Developmental alteration of rat brain synaptic membranes. Reaction of glycoproteins with plant lectins.

Synaptic membranes were isolated from the forebrains of rats of increasing postnatal ages. Developmentally related changes in the structure and concnetration of synaptic membrane glycoproteins were indicated by: (1) a 2--3 fold increase in glycoprotein sialic acid between 5 and 60 days; (2) a similar increase in the number of membrane receptors for the lectins concanavalin A and wheat germ agglutinin; (3) transient increases between 10 and 17 days in the receptors for lentil and castor bean lectins and (4) an age dependent stimulation of castor bean lectin binding by neuraminidase. Labelling of SDS polysacrylamide gels of synaptic membranes with [125I]concanavalin A or wheat germ agglutinin revealed specific, age dependent changes in the lectin binding properties of individual molecular weight classes of glycoproteins. Differences in the glycoproteins composition of synaptic junctional complexes isolated from 10 and 28-day-old brains were also revealed by lectin binding studies. The results indicate that the number and structure of oligosaccharides associated with synaptic membrane glycoproteins are under developmental regulation.

Acetylcholinesterase↗