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Query: UMLS:C0231530 (twitching)
 2,043 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Species-specific binding between the flagellar surfaces of mating types plus and minus (mt+ and mt-) gametes of Chlamydomonas eugametos is mediated by mating type-specific agglutinins. Their interaction triggers several mating responses that are necessary for cell fusion, such as flagellar twitching, flagellar tip activation, redistribution of agglutinin molecules to the flagellar tip (tipping), and mating structure activation. Earlier, we reported that a monoclonal antibody (mAb 66.3) can induce mating reactions by cross-linking the agglutinins (Homan, W. L., A. Musgrave, H. de Nobel, R. Wagter, A. H. J. Kolk, D. de Wit, and H. van den Ende. 1988. J. Cell Biol. 107:177-189). Here we report that the lectin wheat germ agglutinin (WGA), which does not bind to the agglutinins, can also invoke all these mating reactions. We show, by immunofluorescence studies using anti-WGA and an agglutinin-specific monoclonal antibody (mAb 66.3), that WGA induces the redistribution of agglutinin to the flagellar tips of mt- gametes. Vice versa, when agglutinin tipping is induced by mAb 66.3, the WGA-binding glycoproteins are also tipped. Under the same conditions, the major flagellar glycoproteins are not redistributed, indicating that membrane transport is limited to a few components. We conclude that each agglutinin is associated with a WGA-binding glycoprotein. When cells lacking agglutinin or cells possessing inactive agglutinins are treated with WGA, mating responses are again elicited. The data suggest that clustering of agglutinin-containing complexes results in the production of intracellular signals, such as cAMP, and the coupling of the complex to a force generating system. In nature, the complexes are clustered via the agglutinins, but artificially they can be clustered by lectins or antibodies directed against other proteins in the complex.
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PMID:Wheat germ agglutinin induces mating reactions in Chlamydomonas eugametos by cross-linking agglutinin-associated glycoproteins in the flagellar membrane. 255 9

Chlamydomonas eugametos gametes agglutinate sexually by their flagellar surfaces. The agglutination factor on mating type minus (mt-) gametes is thought to be a glycoprotein named PAS-1.2. To test this idea, an antiserum was raised against purified PAS-1.2, which reacted with isolated PAS-1.2 (immunoprecipitation tests) and blocked the ability of isolated PAS-1.2 to induce sexual twitching in mt+ gametes. When tested with living cells, the antiserum specifically agglutinated mt- gametes and induced a reaction resembling twitching. Mt+ flagella were shown to bind the antiserum (indirect immunofluorescence) but much less than mt- gametes. Mt- gametes pretreated with Fab fragments of the antiserum were unable to reproduce sexually, while treated mt+ gametes were unaffected. This effect presumably results from the ability of the serum to block mt- sexual agglutination, for mt- isoagglutinin was completely inactivated by the serum, while mt+ isoagglutinin was unaffected. It is therefore argued that PAS-1.2 is the in vivo mt- agglutination factor. However it is shown that the antiserum was able to react in vitro not only with PAS-1.2 but with several other proteins in both mt- and mt+ flagella.
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PMID:An antiserum against a glycoprotein functional in flagellar adhesion between Chlamydomonas eugametos gametes. 617 93

Radial spokes are a conserved axonemal structural complex postulated to regulate the motility of 9 + 2 cilia and flagella via a network of phosphoenzymes and regulatory proteins. Consistently, a Chlamydomonas radial spoke protein, RSP3, has been identified by RII overlays as an A-kinase anchoring protein (AKAP) that localizes the cAMP-dependent protein kinase (PKA) holoenzyme by binding to the RIIa domain of PKA RII subunit. However, the highly conserved docking domain of PKA is also found in the N termini of several AKAP-binding proteins unrelated to PKA as well as a 24-kDa novel spoke protein, RSP11. Here, we report that RSP11 binds to RSP3 directly in vitro and colocalizes with RSP3 toward the spoke base near outer doublets and dynein motors in axonemes. Importantly, RSP11 mutant pf25 displays a spectrum of motility, from paralysis with flaccid or twitching flagella as other spoke mutants to wildtype-like swimming. The wide range of motility changes reversibly depending on the condition of liquid media without replacing defective proteins. We postulate that radial spokes use the RIIa/AKAP module to regulate ciliary and flagellar beating; absence of the spoke RIIa protein exposes a medium-sensitive regulatory mechanism that is not obvious in wild-type Chlamydomonas.
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PMID:The flagellar motility of Chlamydomonas pf25 mutant lacking an AKAP-binding protein is overtly sensitive to medium conditions. 1626 72

Chlamydomonas eugametos gametes of opposite mating type make cell-cell contact via their flagellar surfaces. This contact triggers an increase in the intracellular level of cyclic AMP (cAMP) and several cellular responses which are necessary for cell fusion. Here, we show that wheat-germ agglutinin, which binds to the flagellar surface and induces all mating responses, also increased the intracellular cAMP level. Dibutyryl-cAMP added to non-mating gametes induced flagellar twitching, cell-wall lysis, mating-structure activation, flagellartip activation and an increase in agglutinability. It did not induce agglutinin transport to the flagellar tip (tipping) and may not be the direct cause of flagellar twitching and flagellar-tip activation. In non-illuminated cells, dibutyryl-cAMP was far more effective in evoking mating reactions than in illuminated cells. Light induced a 50% decrease in the cAMP level within 1 min. Adenylate cyclase was found to be associated with cell membranes but only 8% of the total was present in the gamete flagella.
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PMID:Cyclic AMP is one of the intracellular signals during the mating of Chlamydomonas eugametos. 2419 33