Enhancer Mutations and Chemical Enhancers
An enhancer mutation can be defined as a second mutation that intensifies the phenotype caused by the first mutation. Enhancement may result from various types of genetic interactions. For instance, two genes may function redundantly. Otherwise, mutations in two genes that are both required for the same function. Genes encoding either components of a protein complex or proteins responsible for sequential steps in a signal transduction pathway or in a biosynthesis pathway are examples. In such cases, the homologous double mutant may exhibit a much stronger phenotype than either single mutant. Enhancer gene screenings in Drosophila receptor tyrosine kinase signaling identified genes for Ras1, a downstream GTPase, Sos, a guanine nucleotide exchange factor for Ras1 [13], and Drk, an SH3-SH2-SH3 adaptor for Sos By utilizing analogy to genetic enhancer screening, chemical enhancer screenings can be performed (Figure 2). Difference between genetics and chemical genetics is ease of dosage manipulation. In vertebrate genetics, dosage manipulations are usually achieved by choosing homozygotes or heterozygotes. Heterozygotes are not always the best dosage for the enhancer screening. However, pharmacological methods theoretically allow unrestricted dosage controls. Chemical enhancements may be well known phenomena as synergistic effects of medicines. A good example is synergy between sulfamethoxazole and trimethoprim that is used in the treatment of bacterial, fungal, and protozoan infections [15]. The combination of sulfamethoxazole and trimethoprim shows much greater effect than when given separately, because they inhibit sequential steps in the folate synthesis pathway. Thus, chemical enhancer screenings may identify synergistic compounds to existing drugs, and may expand therapeutic targets
เพิ่มที่กลายพันธุ์และสารเคมีเพิ่ม An enhancer mutation can be defined as a second mutation that intensifies the phenotype caused by the first mutation. Enhancement may result from various types of genetic interactions. For instance, two genes may function redundantly. Otherwise, mutations in two genes that are both required for the same function. Genes encoding either components of a protein complex or proteins responsible for sequential steps in a signal transduction pathway or in a biosynthesis pathway are examples. In such cases, the homologous double mutant may exhibit a much stronger phenotype than either single mutant. Enhancer gene screenings in Drosophila receptor tyrosine kinase signaling identified genes for Ras1, a downstream GTPase, Sos, a guanine nucleotide exchange factor for Ras1 [13], and Drk, an SH3-SH2-SH3 adaptor for Sos By utilizing analogy to genetic enhancer screening, chemical enhancer screenings can be performed (Figure 2). Difference between genetics and chemical genetics is ease of dosage manipulation. In vertebrate genetics, dosage manipulations are usually achieved by choosing homozygotes or heterozygotes. Heterozygotes are not always the best dosage for the enhancer screening. However, pharmacological methods theoretically allow unrestricted dosage controls. Chemical enhancements may be well known phenomena as synergistic effects of medicines. A good example is synergy between sulfamethoxazole and trimethoprim that is used in the treatment of bacterial, fungal, and protozoan infections [15]. The combination of sulfamethoxazole and trimethoprim shows much greater effect than when given separately, because they inhibit sequential steps in the folate synthesis pathway. Thus, chemical enhancer screenings may identify synergistic compounds to existing drugs, and may expand therapeutic targets
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เพิ่มการกลายพันธุ์และสารเคมีเพิ่ม
เป็น Enhancer การกลายพันธุ์สามารถถูกกำหนดเป็นสองการกลายพันธุ์ที่ intensifies การเกิดจากการกลายพันธุ์ก่อน การเพิ่มประสิทธิภาพอาจเป็นผลจากประเภทต่างๆของปฏิสัมพันธ์ทางพันธุกรรม ตัวอย่างเช่นสองยีนอาจทำงานโดยไม่จำเป็น มิฉะนั้น การกลายพันธุ์ในยีนสองที่ทั้งสองเป็นฟังก์ชันเดียวกัน Genes encoding either components of a protein complex or proteins responsible for sequential steps in a signal transduction pathway or in a biosynthesis pathway are examples. In such cases, the homologous double mutant may exhibit a much stronger phenotype than either single mutant. Enhancer gene screenings in Drosophila receptor tyrosine kinase signaling identified genes for Ras1, a downstream GTPase, Sos, a guanine nucleotide exchange factor for Ras1 [13], and Drk, an SH3-SH2-SH3 adaptor for Sos By utilizing analogy to genetic enhancer screening, chemical enhancer screenings can be performed (Figure 2). Difference between genetics and chemical genetics is ease of dosage manipulation. In vertebrate genetics, dosage manipulations are usually achieved by choosing homozygotes or heterozygotes. Heterozygotes are not always the best dosage for the enhancer screening. However, pharmacological methods theoretically allow unrestricted dosage controls. Chemical enhancements may be well known phenomena as synergistic effects of medicines. A good example is synergy between sulfamethoxazole and trimethoprim that is used in the treatment of bacterial, fungal, and protozoan infections [15]. The combination of sulfamethoxazole and trimethoprim shows much greater effect than when given separately, because they inhibit sequential steps in the folate synthesis pathway. Thus, chemical enhancer screenings may identify synergistic compounds to existing drugs, and may expand therapeutic targets
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