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Mutant

About: Mutant is a research topic. Over the lifetime, 74520 publications have been published within this topic receiving 3477079 citations.


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Journal ArticleDOI
28 Jun 1991-Cell
TL;DR: Four genes, BUD1-BUD4, necessary for the axial pattern are identified by isolating mutants of alpha cells that do not exhibit this pattern, indicating the existence of a basal budding pattern, requiring no BUD products, that is random.

405 citations

Journal ArticleDOI
TL;DR: Results support the idea that sequential proteolysis by caspase 3 and calpain may regulate huntingtin function at membranes and produce N-terminal mutant fragments that aggregate and cause cellular dysfunction in HD.
Abstract: The Huntington's disease (HD) mutation is a polyglutamine expansion in the N-terminal region of huntingtin (N-htt). How neurons die in HD is unclear. Mutant N-htt aggregates in neurons in the HD brain; expression of mutant N-htt in vitro causes cell death. Other in vitro studies show that proteolysis by caspase 3 could be important in regulating mutant N-htt function, but there has been no direct evidence for caspase 3-cleaved N-htt fragments in brain. Here, we show that N-htt fragments consistent with the size produced by caspase 3 cleavage in vitro are resident in the cortex, striatum, and cerebellum of normal and adult onset HD brain and are similar in size to the fragments seen after exogenous expression of human huntingtin in mouse clonal striatal neurons. HD brain extracts treated with active caspase 3 had increased levels of N-htt fragments. Compared with the full-length huntingtin, the caspase 3-cleaved N-htt fragments, especially the mutant fragment, preferentially segregated with the membrane fraction. Partial proteolysis of the human caspase 3-cleaved N-htt fragment by calpain occurred in vitro and resulted in smaller N-terminal products; products of similar size appeared when mouse brain protein extracts were treated with calpain. Results support the idea that sequential proteolysis by caspase 3 and calpain may regulate huntingtin function at membranes and produce N-terminal mutant fragments that aggregate and cause cellular dysfunction in HD.

405 citations

Journal ArticleDOI
TL;DR: It is demonstrated that PAL and CHS mRNAs accumulate in leaves of Arabidopsis thaliana (L.) Heynh upon exposure to low temperature in a light-dependent manner and that light may also be implicated in the regulation of the CHS gene in response to bacterial infiltration.
Abstract: Anthocyanins, which accumulate in leaves and stems in response to low temperature and changes in light intensity, are synthesized through the phenylpropanoid pathway that is controlled by key enzymes that include phenylalanine ammonia-lyase (PAL) and chalcone synthase (CHS) In this work we demonstrate that PAL and CHS mRNAs accumulate in leaves of Arabidopsis thaliana (L) Heynh upon exposure to low temperature in a light-dependent manner The regulation of the PAL1 gene expression by low temperature and light was examined by analyzing the expression of the [beta]-glucuronidase (uidA) reporter gene in transgenic Arabidopsis plants containing the uidA gene of Escherichia coli under the control of the PAL1 promoter The results indicate that the accumulation of PAL1 mRNA is transcriptionally regulated Histochemical staining for [beta]-glucuronidase activity showed that the PAL1 promoter is preferentially activated in photosynthetically active cells, paralleling anthocyanin accumulation Moreover, we show that light may also be implicated in the regulation of the CHS gene in response to bacterial infiltration Finally, using two transparent testa Arabidopsis mutants that are unable to accumulate anthocyanins, we demonstrate that these pigments are not required for successful development of freezing tolerance in this species

405 citations

Journal ArticleDOI
TL;DR: Results suggest that MSG2/IAA19 and NPH4/ARF7 may constitute a negative feedback loop to regulate differential growth responses of hypocotyls and lateral root formation.
Abstract: We have isolated a dominant, auxin-insensitive mutant of Arabidopsis thaliana, massugu2 (msg2), that displays neither hypocotyl gravitropism nor phototropism, fails to maintain an apical hook as an etiolated seedling, and is defective in lateral root formation. Yet other aspects of growth and development of msg2 plants are almost normal. These characteristics of msg2 are similar to those of another auxin-insensitive mutant, non-phototropic hypocotyl4 (nph4), which is a loss-of-function mutant of AUXIN RESPONSE FACTOR7 (ARF7) (Harper et al., 2000). Map-based cloning of the MSG2 locus reveals that all four mutant alleles result in amino acid substitutions in the conserved domain II of an Auxin/Indole-3-Acetic Acid protein, IAA19. Interestingly, auxin inducibility of MSG2/IAA19 gene expression is reduced by 65% in nph4/arf7. Moreover, MSG2/IAA19 protein binds to the C-terminal domain of NPH4/ARF7 in a Saccharomyces cerevisiae (yeast) two-hybrid assay and to the whole latter protein in vitro by pull-down assay. These results suggest that MSG2/IAA19 and NPH4/ARF7 may constitute a negative feedback loop to regulate differential growth responses of hypocotyls and lateral root formation.

405 citations

Journal ArticleDOI
TL;DR: A new secretory mutant, sec61, is uncovered that is thermosensitive for growth and that accumulates multiple secretory and vacuolar precursor proteins that have not acquired any detectable posttranslational modifications associated with translocation into the ER.
Abstract: We have devised a genetic selection for mutant yeast cells that fail to translocate secretory protein precursors into the lumen of the endoplasmic reticulum (ER). Mutant cells are selected by a procedure that requires a signal peptide-containing cytoplasmic enzyme chimera to remain in contact with the cytosol. This approach has uncovered a new secretory mutant, sec61, that is thermosensitive for growth and that accumulates multiple secretory and vacuolar precursor proteins that have not acquired any detectable posttranslational modifications associated with translocation into the ER. Preproteins that accumulate at the sec61 block sediment with the particulate fraction, but are exposed to the cytosol as judged by sensitivity to proteinase K. Thus, the sec61 mutation defines a gene that is required for an early cytoplasmic or ER membrane-associated step in protein translocation.

405 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20241
20237,150
20226,747
20211,630
20201,916
20191,849