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Nuclear Transport Proteins

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Description	Biochem/physiol Actions	Product #
Importin α2 human ≥90% (SDS-PAGE), recombinant, expressed in Escherichia coli (as N-terminal histidine tagged), buffered aqueous glycerol solution	The importin α (karyopherin α, Impα) family consists of nuclear transport adapter proteins of approximately 60 kDa. Importin α links the import receptor, importin β (karyopherin β, Impβ) with cargo proteins containing classical nuclear localization signal (NLS). Binding of importin β to importin α increases the affinity of the importin α NLS binding domain to the cargo protein. Formation of the Impα/Impβ/Cargo complex triggers the binding of importin β to the nuclear pore complex (NPC) and subsequent import of the entire complex into the nucleus. Inside the nucleus, the cargo protein and importin α are released from the complex upon binding of Ran-GTP to importin β and importin α and then recycled back to the cytoplasm by CAS, an importin α specific export receptor.	I9656
Importin β1 human ≥80% (SDS-PAGE), recombinant, expressed in Escherichia coli (N-terminal histdine-tagged), buffered aqueous glycerol solution	Importin β, an import receptor, is a prototype of the nuclear transport receptor family, which comprises in human more than 20 proteins (90-180 kDa). These proteins interact directly with nuclear pore complex (NPC) and mediate nucleocytoplasmic transport. Importin β imports into the nucleus proteins carrying canonical nuclear localization signals (NLS) as well as UsnRNAs, which it binds via adaptor proteins, importin α and snurpotin-1 respectively. Importin β also binds directly, without adaptors, ribosomal proteins, Smad proteins, and virus derived proteins such as HIV Rev and Tat, that contain non classical NLS. In addition, Improtin b has been shown to be involved in the nuclear envelope assembly process. The mechanism of importin β action in nuclear import can be demonstrated by the well-studied import of proteins containing classical NLS. Importin β forms a complex with Importin α, which, in turn, binds the cargo protein via its NLS. The Impβ/Impα/cargo complex translocates into the nucleus. When the complex reaches the nuclear site of the NPC, Ran-GTP binds the Impβ to form Impβ/Ran-GTP complex and released the Impα and the cargo protein. The Impβ/Ran-GTP complex is then exported to the cytoplasm where the complex dissociates upon hydrolysis of GTP to GDP, making Impβ ready for a new import cycle.	I9781
Import Ligand, Fluorescent buffered aqueous solution	Common NLS (nuclear localization signal) for semi-synthetic import ligands is the SV-40 large T-antigen NLS, amino acid sequence CGGGPKKKRKVED covalently linked to rhodamine-labeled albumin. Enables observation of the nuclear import process in permeabilized cells by fluorescence microscopy. Proteins due to enter the cell nucleus are ‘labeled’ by nuclear localization signals (NLS). The canonical NLS consists of either a single or bipartite stretch of primarily basic amino acids. The NLS is recognized in the cytoplasm by its receptor importin α. Importin α forms a complex with another protein, importin β. This interaction then targets the import complex to the nuclear pore complex (NPC). Passage of the import substrate from the NPC to the nuclear interior requires two additional factors: p10 and the small GTPase Ran. In the nucleus, the binding of Ran-GTP to importin β releases the transported protein from the complex. A commonly used NLS (nuclear localization signal) for semi-synthetic import ligands is the SV-40 large T-antigen NLS, a 13 amino acid peptide of the sequence CGGGPKKKRKVED, which is covalently linked to rhodamine-labeled albumin. This enables observation of the nuclear import process in permeabilized cells by fluorescence microscopy using a filter suitable for TRITC/Cy3.	I9906
Nuclear Transport Factor 2 human >90% (SDS-PAGE), recombinant, expressed in Escherichia coli, lyophilized powder	Mediates the nuclear import of RanGDP, driving the nuclear accumulation of Ran. This process is essential for maintaining the cellular nuclear transport and for cell viability. NTF2, which possesses non-overlapping binding sites for both RanGDP and nucleoporin FxFG repeats, binds RanGDP in the cytoplasm and carries it via the nuclear pore complex (NPC) by binding to the FxFG-repeats, which allows rapid attachment and detachment of NTF2 to the nucleoporins while it passes through the NPC. At the nuclear side of the NPC, the release of RanGDP from NTF2 may be promoted by dissociation of the NTF2 to its monomers. Mediates the nuclear import of RanGDP, driving the nuclear accumulation of Ran. This process is essential for maintaining the cellular nuclear transport and for cell viability.	N4160
Nuclear Transport Factor 2−Agarose saline suspension	NTF2 is a small homodimeric protein that interacts simultaneously with both Ran-GDP and FxFG nucleoporins. The interaction between NTF2 and Ran-GDP is essential for the import of Ran into the nucleus, thus crucial for maintaining the cellular nuclear transport and cell viability. NTF2-agarose affinity resin is a useful tool for studying nuclear transport and the depletion of Ran-GDP from cell extracts.	N9285
RAN human >90% (SDS-PAGE), recombinant, expressed in Escherichia coli (as N-terminal histidine tagged), buffered aqueous glycerol solution	Ran (TC4), a small GTP binding protein, is the heart of the nuclear transport process. It is involved in the directionality of the process that is regulated by GTP hydrolysis. Ran shuttles between the nucleus and the cytoplasm. In the nucleus, it exists in Ran-GTP form, which is maintained by the Ran-Guanine nucleotide exchange protein, RCC1, a nucleus specific, chromatin bound protein. Ran-GTP forms complexes with transport proteins that shuttle from the nucleus to the cytoplasm i.e. improtin β, CRM1/exportin1. In the cytoplasm, Ran intrinsic GTPase activity is stimulated by Ran-GAP causing the hydrolysis of GTP to GDP and disassembly of the resulted Ran-GDP from the transport protein. Ran-GDP reenters the nucleus by active transport as NTF2/Ran-GDP complex.	R3152

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