Document Detail

A novel lysine-rich domain and GTP binding motifs regulate the nucleolar retention of human guanine nucleotide binding protein, GNL3L.
MedLine Citation:
PMID:  17034816     Owner:  NLM     Status:  MEDLINE    
A variety of G-proteins and GTPases are known to be involved in nucleolar function. We describe here a new evolutionarily conserved putative human GTPase, guanine nucleotide binding protein-like 3-like (GNL3L). Genes encoding proteins related to GNL3L are present in bacteria and yeast to metazoa and suggests its critical role in development. Conserved domain search analysis revealed that the GNL3L contains a circularly permuted G-motif described by a G5-G4-G1-G2-G3 pattern similar to the HSR1/MMR1 GTP-binding protein subfamily. Highly conserved and critical residues were identified from a three-dimensional structural model obtained for GNL3L using the crystal structure of an Ylqf GTPase from Bacillus subtilis. We demonstrate here that GNL3L is transported into the nucleolus by a novel lysine-rich nucleolar localization signal (NoLS) residing within 1-50 amino acid residues. NoLS identified here is necessary and sufficient to target the heterologous proteins to the nucleolus. We show for the first time that the lysine-rich targeting signal interacts with the nuclear transport receptor, importin-beta and transports GNL3L into the nucleolus. Interestingly, depletion of intracellular GTP blocks GNL3L accumulation into the nucleolar compartment. Furthermore, mutations within the G-domains alter the GTP binding ability of GNL3L and abrogate wild-type nucleolar retention even in the presence of functional NoLS, suggesting that the efficient nucleolar retention of GNL3L involves activities of both basic NoLS and GTP-binding domains. Collectively, these data suggest that GNL3L is composed of distinct modules, each of which plays a specific role in molecular interactions for its nucleolar retention and subsequent function(s) within the nucleolus.
M R K Subba Rao; Gita Kumari; D Balasundaram; R Sankaranarayanan; S Mahalingam
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-09-08
Journal Detail:
Title:  Journal of molecular biology     Volume:  364     ISSN:  0022-2836     ISO Abbreviation:  J. Mol. Biol.     Publication Date:  2006 Dec 
Date Detail:
Created Date:  2006-11-20     Completed Date:  2007-01-22     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  2985088R     Medline TA:  J Mol Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  637-54     Citation Subset:  IM    
Laboratory of Molecular Virology, Centre for DNA Fingerprinting and Diagnostics, ECIL Road, Nacharam, Hyderabad 500076, India.
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MeSH Terms
Active Transport, Cell Nucleus
Amino Acid Motifs
Cell Nucleolus / metabolism*
GTP-Binding Proteins / metabolism*
Guanosine Triphosphate / metabolism
Nuclear Localization Signals
Nuclear Proteins / metabolism*
Protein Structure, Tertiary
beta Karyopherins
Reg. No./Substance:
0/GNL3L protein, human; 0/Nuclear Localization Signals; 0/Nuclear Proteins; 0/beta Karyopherins; 56-87-1/Lysine; 86-01-1/Guanosine Triphosphate; EC 3.6.1.-/GTP-Binding Proteins

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