The initial rate of nuclear accumulation was 011 ms

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The initial rate of nuclear accumulation was 0.11 " M/s, corresponding to 28 translocations·NPC–1·s –1 or a mass flow of 17 MDa·NPC–1·s–1. Fast rate of karyopherin-mediated import into nuclei- (There is a lag in the initial rate?)
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Dynamics of interaction between nucleoporins, karyopherin and cargo- (slow)
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Low affinity, High off-rate Low affinity High off-rate Hi affinity, Low off-rate Hi affinity, Low off-rate Medium affinity, Medium off-rate Medium affinity, Medium off-rate import export RanGTP Ran GAP + Karyopherins must bind two FG Nups simultaneously and with different affinities/off rates for this mechanism to work. Also, the highest affinity site must be emptied efficiently. The affinity gradient model for karyopherin movement across the NPC-
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The virtual gate model and entropic exclusion of large proteins- Predicts - Central transporter is an open tube that allows diffusion of karyopherin -cargo complexes after entering through the “entropic gate.” All importins and exportins undergo trapping at the periphery of the NPC, to promote vectoriality and allow time for RanGTP to function
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The “selective phase” model for translocation across the NPC- Predicts - > FG Nup filaments may be interacting with each other via phenylalanines in FG motifs to form a cohesive meshwork that sieves particles by size exclusion Importins and exportins displace filaments and FG-FG interactions as they move across the NPC; then the filaments re-seal gaps so as to maintain permeability barrier. This arrangement could also allow small particles to diffuse across while accommodate karyopherins carrying particles of all shapes and sizes Disruption of meshwork by hydrophobic compound-hexanediol
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1. The affinity gradient model proposes that FG domains of nups are arranged within the NPC in a manner that present docking sites for Kaps in an increasing gradient of affinity, with the highest affinity site at the distal/exit location. 2. The virtual gate model proposes that the NPC channel consists of a narrow central tube. Binding to peripheral FG-repeat-containing nucleoporins increases the probability of entering the channel and thus facilitates the translocation step. Translocation itself occurs by Brownian motion. 3. The selective phase model puts forward that the NPC channel represents a selective phase consisting of a meshwork formed by weakly interacting, hydrophobic FG-rich repeats. The selective phase can only be entered and permeated by transport receptors that can interact with FG-repeats and disrupt the meshwork. 4. The “oily-spaghetti” model proposes that the open NPC channel is filled by hydrophobic, non -interacting FG-repeats that can be pushed aside by receptor-cargo complexes but prevent the passage of other molecules.
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