The_nucleus_and_nuclear_transport

The_nucleus_and_nuclear_transport - Classic = KKKRK or KRVK...

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The Nucleus and Nuclear Transport 1. Nuclear Envelope 2. Nuclear Pore Complex 3. Nuclear Localization Signals 4. Nuclear Import/Export Receptors 5. Energy for Nuclear Transport driven by GTP hydrolysis 6. Regulation of transport
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Nuclear Envelope inner membrane reinforced by nuclear lamins A,B and C binding sites for chromatin outer membrane continuous with ER Selectivity is mediated by nuclear pore complexes
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Nuclear Pore Complexes Made up nucleoporins Typical cell has 3-4 thousand complexes Structurally have 4 major building blocks: column subunits annular subunits lumenal subunits ring subunits Pore is 90-100 nm in diameter Aqueous channel only 9 nm in diameter 5,000 daltons or less will free diffuse
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11.4 Proteins with a nuclear-localization signal (NLS) are recognized by receptors and transported into the nucleus Figure 11-35 Nuclear localization signal Present only on nuclear proteins can be either signal sequence or patch Typically very rich in lys and arg (+ charges)
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Unformatted text preview: Classic = KKKRK or KRVK Bipartite = VKRx 10 KKKKLD Nuclear Import/Export receptors Family of proteins called karyopherins cytosolic Bind FG repeats of NPC Each receptor specific for particular localization signal Direction of transport is determined by sequence signals Sequence Substrate Vehicle Classic NLS P KKKRK v SV40 large T-antigen Importin Bipartite NLS v KR x 10 KK KK LD nucleoplas min importin and Leu-rice NES L Q L PP L E R L T L protein kinase A inhibitor exportin-1 Energy for transport driven by GTP hydrolysis Nuclear transport is energy dependent Motor that drives transport is the GTPase protein Ran Ran is regulated by two proteins Ran GTPase activating protein (Ran-GAP) found only in cytosol Ran guanine exchange factor (Ran-GEF) found only in nucleus Model of nuclear transport Regulation of Transport 1. Rate of transport 2. Phosphorylation of NLS 3. Masking NLS...
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The_nucleus_and_nuclear_transport - Classic = KKKRK or KRVK...

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