The polybasic region of Ras and Rho family small GTPases: a regulator of protein interactions and membrane association and a site of nuclear localization signal sequences

2003 ◽  
Vol 15 (12) ◽  
pp. 1071-1080 ◽  
Author(s):  
Carol L Williams
Keyword(s):  
Nuclear Localization ◽  
Protein Interactions ◽  
Nuclear Localization Signal ◽  
Small Gtpases ◽  
Membrane Association ◽  
Signal Sequences ◽  
Localization Signal ◽  
Rho Family ◽  
A Site ◽  
Polybasic Region

scholarly journals HCF-1 Amino- and Carboxy-Terminal Subunit Association through Two Separate Sets of Interaction Modules: Involvement of Fibronectin Type 3 Repeats

2000 ◽  
Vol 20 (18) ◽  
pp. 6721-6730 ◽  
Author(s):  
Angus C. Wilson ◽  
Michael Boutros ◽  
Kristina M. Johnson ◽  
Winship Herr
Keyword(s):  
Nuclear Localization ◽  
Protein Interactions ◽  
Nuclear Localization Signal ◽  
Regulatory Protein ◽  
Proteolytic Processing ◽  
Structural Motif ◽  
Localization Signal ◽  
Carboxy Terminal ◽  
Type 3 ◽  
Fibronectin Type

ABSTRACT When herpes simplex virus infects permissive cells, the viral regulatory protein VP16 forms a specific complex with HCF-1, a preexisting nuclear protein involved in cell proliferation. The majority of HCF-1 in the cell is a complex of associated amino (HCF-1N)- and carboxy (HCF-1C)-terminal subunits that result from an unusual proteolytic processing of a large precursor polypeptide. Here, we have characterized the structure and function of sequences required for HCF-1N and HCF-1C subunit association. HCF-1 contains two matched pairs of self-association sequences called SAS1 and SAS2. One of these matched association sequences, SAS1, consists of a short 43-amino-acid region of the HCF-1N subunit, which associates with a carboxy-terminal region of the HCF-1Csubunit that is composed of a tandem pair of fibronectin type 3 repeats, a structural motif known to promote protein-protein interactions. Unexpectedly, the related protein HCF-2, which is not proteolyzed, also contains a functional SAS1 association element, suggesting that this element does not function solely to maintain HCF-1N and HCF-1C subunit association. HCF-1N subunits do not possess a nuclear localization signal. We show that, owing to a carboxy-terminal HCF-1 nuclear localization signal, HCF-1Csubunits can recruit HCF-1N subunits to the nucleus.

scholarly journals Characterization of a Drosophila phosphorylation-dependent nuclear-localization-signal-binding protein

1997 ◽  
Vol 328 (3) ◽  
pp. 821-826
Author(s):  
Imre CSERPÁN ◽  
Endre MÁTHÉ ◽  
András PATTHY ◽  
Andor UDVARDY
Keyword(s):  
Nuclear Localization ◽  
Protein Interactions ◽  
Nuclear Localization Signal ◽  
Binding Protein ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Localization Signal ◽  
Co Precipitation ◽  
Drosophila Embryos

A 94 kDa nuclear-localization-signal (NLS)-binding protein was purified from Drosophila embryos. The NLS of the simian-virus-40 T-antigen is specifically bound by the dephosphorylated form of the protein. After phosphorylation, the affinity of the protein for the NLS is sharply decreased. In the dephosphorylated form, p94 (protein of 94 kDa) is the major NLS-binding protein in Drosophila embryos. Immunoprecipitation confirmed the ATP-dependent phosphorylation of p94, and co-precipitation of two additional phosphorylated proteins, indicated that the NLS-binding protein is part of a larger complex in Drosophila embryos. In agreement with the immunoprecipitation results, cross-linking experiments demonstrated the interaction of p94 with three additional proteins. These protein-protein interactions were also phosphorylation-dependent.

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