Lecture 4 Regulation of Transcription Factor Activity by Extracellular Signals

Lecture 4 Regulation of Transcription Factor Activity by Extracellular Signals

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Unformatted text preview: IPHY 2060 Lecture 4: Regulation of Transcription Factor Activity by Extracellular Signals Key points from last time • A gene is a DNA sequence that codes for an RNA and thus a protein • All cells have the same genes, they just activate different subsets of them • Genes are turned on and off by transcription factors, proteins that bind to specific sequences in the regulatory region of the gene • Transcription factor activity can be modified by phosphorylation Regulation of transcription factor nuclear import/export by phosphorylation Key Point #3: Import and export of substances into and out of the nucleus is a regulated process Regulation of nuclear transport • Nucleus is surrounded by a double-walled nuclear membrane • The nuclear membrane contains pores where the two membranes meet The Nuclear Pore Complex • Consists of 50-100 proteins called nucleoporins • Small molecules can diffuse freely through nuclear pore • The nuclear pore actively controls transport of large molecules into and out of the nucleus Nucleus Cytoplasm Nuclear Import of Proteins • Requires nuclear localization signal or NLS on the protein—a sequence of basic amino acids near the carboxy-terminus of the protein • Also requires proteins called importins that bind to the NLS of the “cargo” protein and to the nucleoporins Nuclear Import of Proteins NLS Cytoplasm Nucleus Importin Step 1: Importin binds to NLS of nuclear protein Nuclear Import of Proteins Cytoplasm Nucleus Importin Step 1: Importin binds to NLS of nuclear protein NLS Nuclear Import of Proteins Cytoplasm Nucleus Importin Step 1: Importin binds to NLS of nuclear protein NLS Step 2: Importin/ protein complex binds to nucleoporins Nuclear Import of Proteins Cytoplasm Nucleus Importin Step 1: Importin binds to NLS of nuclear protein NLS Step 2: Importin/ protein complex binds to nucleoporins Nuclear Import of Proteins Cytoplasm Nucleus Importin Step 1: Importin binds to NLS of nuclear protein NLS Step 2: Importin/ protein complex binds to nucleoporins Step 3: Importin/ protein complex is transported through the nuclear pore and into nucleus Nuclear Import of Proteins Cytoplasm Nucleus Step 1: Importin binds to NLS of nuclear protein Step 2: Importin/ protein complex binds to nucleoporins Step 3: Importin/ protein complex is transported through the nuclear pore and into nucleus Importin NLS Nuclear Import of Proteins Cytoplasm Nucleus Step 1: Importin binds to NLS of nuclear protein Step 2: Importin/ protein complex binds to nucleoporins Step 3: Importin/ protein complex is transported through the nuclear pore and into nucleus Importin NLS Nuclear Import of Proteins Cytoplasm Nucleus Step 1: Importin binds to NLS of nuclear protein Step 2: Importin/ protein complex binds to nucleoporins Step 3: Importin/ protein complex is transported through the nuclear pore and into nucleus Importin NLS Step 4: Importin unbinds from protein Nuclear Import of Proteins...
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This note was uploaded on 08/11/2010 for the course IPHY 3060 taught by Professor Allen,davi during the Fall '09 term at Colorado.

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Lecture 4 Regulation of Transcription Factor Activity by Extracellular Signals

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