Sandbox 125: Difference between revisions

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Proteopedia Page Contributors and Editors (what is this?)Proteopedia Page Contributors and Editors (what is this?)

Wayne Decatur, Student, Marisa L. VanBrakle, Allison Granberry

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 <StructureSection load='1QBK' size=550 side=right scene='1QBK'/Com_view/1'>
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+==='''Identification of the cargo and Transport through the NPC'''===
+In eukaryotes, proteins must be transported in and out of the nucleus. This nucleocytoplasmic transport of proteins across the nuclear envelope must occur through the gateway of the NPC. The NPC is a large structure consisting of 456 constituent binding proteins called nucleoporins (Nups).1  Movement through the NPC is facilitated transport that relies on interaction with specific Nups.  Importins and exportins are proteins that aid this facilitated transport by both binding to a specific cargo to be transported and interacting with specific Nups located in the central channel of the NPC.2
+Karyopherinβ is a group of proteins that is composed of both importins and exportins. Importins are proteins that carry cargos into the nucleus while exportins serve the opposite function. As of today, twenty different Kapβs have been identified. Each of these Kapβs is capable of recognizing and transporting a specific group of cargos. In order to bind to its cargo a Kapβ has to recognize a Nuclear Localizaton or Export Signal (NLS or NES) is located in the polypeptide chain of the cargo. These signals can vary from 7 amino acids to longer than 100 amino acids in length.
+An importin, such as Kapβ2, binds to a specific cargo by recognition of an NLS and carries the cargo through the NPC by interacting with intrinsically disordered Nups called FG-Nups. FG-Nups line the passageway of the NPC and contain repeats of phenylalanine and glycine. These unstructured FG-Nups form a low-density cloud within the central channel extending from the cytoplasm to the nucleoplasm. The cloud acts as an effective exclusion filter for those particles that do not contain FG repeat binding sites. This is referred to as the zone of selectivity.