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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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TL;DR: Genetic epistasis data are consistent with a model that TSC1 and Tsc2 function together in the insulin signaling pathway and show that the Tsc1 protein binds to Drosophila T sc2 in vitro.
516 citations
TL;DR: Findings implicate damage from action of spinal cord-specific factors that recruit mutant SOD1 to spinal mitochondria as the basis for their selective toxicity in ALS.
515 citations
TL;DR: A new mutant is described, hfr1 (long hypocotyl in far-red), that exhibits a reduction in seedling responsiveness specifically to continuous far- red light (FRc), thereby suggesting a locus likely to be involved in phytochrome A (phyA) signal transduction.
Abstract: Phytochromes are informational photoreceptors through which plants adapt their growth and development to prevailing light conditions. These adaptations are effected primarily through phytochrome regulation of gene expression by mechanisms that remain unclear. We describe a new mutant, hfr1 (long hypocotyl in far-red), that exhibits a reduction in seedling responsiveness specifically to continuous far-red light (FRc), thereby suggesting a locus likely to be involved in phytochrome A (phyA) signal transduction. Using an insertionally tagged allele, we cloned the HFR1 gene and subsequently confirmed its identity with additional alleles derived from a directed genetic screen. HFR1 encodes a nuclear protein with strong similarity to the bHLH family of DNA-binding proteins but with an atypical basic region. In contrast to PIF3, a related bHLH protein previously shown to bind phyB, HFR1 did not bind either phyA or B. However, HFR1 did bind PIF3, suggesting heterodimerization, and both the HFR1/PIF3 complex and PIF3 homodimer bound preferentially to the Pfr form of both phytochromes. Thus, HFR1 may function to modulate phyA signaling via heterodimerization with PIF3. HFR1 mRNA is 30-fold more abundant in FRc than in continuous red light, suggesting a potential mechanistic basis for the specificity of HFR1 to phyA signaling.
515 citations
TL;DR: It is shown that the mouse cell line ts85, a previously isolated cell cycle mutant, is temperature-sensitive in ubiquitin-protein conjugation, and that this effect is due to the specific thermolability of the ts85 ubiquitIn-activating enzyme (E1).
515 citations
TL;DR: The identification of a new mutant Arabidopsis locus, srl2, which confers selective hypersensitivity to continuous red, but not far‐red, light is reported, suggesting that PIF4 may function specifically in a branch of the phyB signaling network that regulates a subset of genes involved in cell expansion.
Abstract: Plants sense and respond to red and far-red light using the phytochrome (phy) family of photoreceptors. However, the mechanism of light signal transduction is not well defined. Here, we report the identification of a new mutant Arabidopsis locus, srl2 (short under red-light 2), which confers selective hypersensitivity to continuous red, but not far-red, light. This hypersensitivity is eliminated in srl2phyB, but not srl2phyA, double mutants, indicating that this locus functions selectively and negatively in phyB signaling. The SRL2 gene encodes a bHLH factor, designated PIF4 (phytochrome-interacting factor 4), which binds selectively to the biologically active Pfr form of phyB, but has little affinity for phyA. Despite its hypersensitive morphological phenotype, the srl2 mutant displays no perturbation of light-induced expression of marker genes for chloroplast development. These data suggest that PIF4 may function specifically in a branch of the phyB signaling network that regulates a subset of genes involved in cell expansion. Consistent with this proposal, PIF4 localizes to the nucleus and can bind to a G-box DNA sequence motif found in various light-regulated promoters.
515 citations