Biomedical subjects

K Terrance

Publications and source records attributed to K Terrance.

5 recordsLinked to original sources

PubMed1987

Pheromone induction of agglutination in Saccharomyces cerevisiae a cells.

a-Agglutinin, the cell surface sexual agglutinin of yeast a cells, was assayed by its ability to bind its complementary agglutinin, alpha-agglutinin. The specific binding of 125I-alpha-agglutinin to a cells treated with the sex pheromone alpha-factor was 2 to 2.5 times that of binding to a cells not treated with alpha-factor. Competition with unlabeled alpha-agglutinin revealed that the increased binding was due to increased cell surface expression of a-agglutinin, with no apparent change in the binding constant. The increase in site number was similar to the increase in cellular agglutinability. Increased expression of a-agglutinin followed the same kinetics as the increase in cellular agglutinability, with a 10-min lag followed by a 15- to 20-min response time. Induction kinetics were similar in cells in phases G1 and G2 of the cell cycle. Maximal expression levels were similar in cells treated with excess pheromone and in cells exposed to pheromone after destruction of constitutively expressed a-agglutinin.

Agglutination↗

PubMed1987

Identification of glycoprotein components of alpha-agglutinin, a cell adhesion protein from Saccharomyces cerevisiae.

Several glycoproteins which inhibit the agglutinability of Saccharomyces cerevisiae mating type a cells were partially purified from extracts of mating type alpha cells. These proteins, called alpha-agglutinin, were labeled with 125I-Bolton-Hunter reagent. The labeled alpha-agglutinin showed specific binding to a cells. Such specific binding approached saturation with respect to agglutinin or cells and was inhibited in the presence of excess unlabeled alpha-agglutinin. Nonspecific binding was similar in a and alpha cells, was neither saturable nor competable, and was three- to fourfold less than the specific binding to a cells at maximum tested agglutinin concentrations. The major a-specific binding species had a low electrophoretic mobility in sodium dodecyl sulfate-polyacrylamide gels and had an apparent molecular weight of 155,000 by rate zonal centrifugation. Endo-N-acetylglucosaminidase H digestion of the purified glycoprotein complex converted the low-mobility material to four major and several minor bands which were resolved by polyacrylamide gel electrophoresis. All but two minor peptides bound specifically to a cells. Analyses of agglutinin from mnn mutants confirmed the deglycosylation results in suggesting that the N-linked carbohydrate portion of alpha-agglutinin was not necessary for activity.

Agglutination↗

PubMed1987

Interaction of alpha-agglutinin with Saccharomyces cerevisiae a cells.

Binding of Saccharomyces cerevisiae alpha-agglutinin to target a cells was assayed by agglutination inhibition and 125I-alpha-agglutinin binding. The assays showed characteristics of equilibrium binding, namely saturability, competability, and the establishment of a kinetic endpoint in the presence of free alpha-agglutinin and free receptor. The binding was heterogeneous, displaying strong binding (10(9) liters/mol) and a weaker interaction. There were about 2 X 10(4) strong binding sites per a cell. Denaturing gels displayed identical labeled species binding to the a cells in the weak and strong interactions. Furthermore, weakly bound material could subsequently bind tightly to fresh a cells, implying that the same species of alpha-agglutinin was bound in the two states.

Agglutination↗

PubMed1984

Different structure-function relationships for alpha-factor-induced morphogenesis and agglutination in Saccharomyces cerevisiae.

Eight synthetic analogs of the mating pheromone alpha-factor-induced morphogenesis and increased agglutinability in a cells. Most analogs induced increased agglutinability at lower concentrations than those at which they induced morphogenesis, but the ratio of the potencies for the two effects varied 140-fold among different analogs. Morphological response to pheromone required exposure for at least 90 min, but increased agglutinability followed exposures of 20 s. Two synthetic analogs induced neither response. In competition experiments, both of these analogs prevented induction of increased agglutinability and morphogenesis by active alpha factor. The inactive peptides blocked increased agglutinability at lower concentrations than those at which they blocked morphogenesis. alpha factors exhibited different structure-function relationships for morphogenesis as compared with agglutinability. Thus, response of Saccharomyces cerevisiae to alpha factor is complex and may be mediated by more than one receptor.

Agglutination↗

PubMed1981

Sexual agglutination in Saccharomyces cerevisiae.

Treatment of either mating type of Saccharomyces cerevisiae with the appropriate sex pheromone increased cell-cell binding in a modified cocentrifugation assay. Constitutive agglutination of haploids was qualitatively similar to pheromone-induced agglutination. Regardless of exposure to pheromone, agglutinable combinations of cells exhibited maximal binding across similar ranges of ionic strength, pH, and temperature. Binding of all combinations was inhibited by 8 M urea, 1 M pyridine, or 0.05% sodium dodecyl sulfate. From alpha-cells we solubilized and partially purified an inhibitor of a-cell agglutinability. This inhibitor reversibly masked all a-cell adhesion sites and inactivated pheromone-treated and control cells with similar kinetics. The inhibitor behaved as a homogeneous species in heat inactivation experiments. Based on these results, we proposed a model for pheromone effects on agglutination in S. cerevisiae.

Agglutination↗