RNA helicase A (RHA), an ATPase/helicase, regulates the gene expression at various steps including transcriptional activation and RNA processing. RHA is known to shuttle between the nucleus and cytoplasm. We identified the nuclear localization signal (NLS) of RHA and analyzed the nuclear import mechanisms. The NLS of RHA (RHA-NLS) consisting of 19 amino acid residues is highly conserved through species and does not have the consensus classical NLS. In vitro nuclear import assays revealed that the nuclear import of RHA was Ran-dependent and mediated with the classical importin-alpha/beta-dependent pathway. The binding assay indicated that the basic residues in RHA-NLS were used for interaction with importin-alpha. Furthermore, the nuclear import of RHA-NLS was supported by importin-alpha1 and preferentially importin-alpha3. Our results indicate that the nuclear import of RHA is mediated by the importin-alpha3/importin-beta-dependent pathway and suggest that the specificity for importin may regulate the functions of cargo proteins.
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http://dx.doi.org/10.1016/j.bbrc.2005.11.161 | DOI Listing |
Adv Protein Chem Struct Biol
January 2025
Neural Development Biology Lab, Department of Life Science, NIT Rourkela, Rourkela, Odisha, India.
The nuclear pore complex, a large multimeric structure consists of numerous protein components, serves as a crucial gatekeeper for the transport of macromolecules across the nuclear envelope in eukaryotic cells. Dysfunction of the NPC has been implicated in various neurodegenerative diseases, including Alzheimer's disease. In AD, Tau aggregates interact with NPC proteins, known as nucleoporins, leading to disruptions in nuclear transport.
View Article and Find Full Text PDFAdv Protein Chem Struct Biol
January 2025
Department of Neurochemistry, National Institute of Mental Health and Neuro Sciences Hospital (NIMHANS), Institute of National Importance, Bangalore, Karnataka, India.
Tau is a well-known microtubule-associated protein and is located in the cytoplasm of neurons, which play a crucial role in Alzheimer's diseases. Due to its preferred binding to DNA sequences found in the nucleolus and pericentromeric heterochromatin, Tau has been found within the cell nucleus, where it may be a nucleic acid-associated protein. Tau has the ability to directly interact with nuclear pore complex nucleoporins, influencing both their structural and functional integrity.
View Article and Find Full Text PDFAdv Protein Chem Struct Biol
January 2025
Department of Medical Oncology (Lab), Dr. B.R. Ambedkar Institute Rotary Cancer Hospital, All India Institute of Medical Sciences, New Delhi, India. Electronic address:
Lamins, which are crucial type V intermediate filament proteins found in the nuclear lamina, are essential for maintaining the stability and function of the nucleus in higher vertebrates. They are classified into A- and B-types, and their distinct expression patterns contribute to cellular survival, development, and functionality. Lamins emerged during the transition from open to closed mitosis, with their complexity increasing alongside organism evolution.
View Article and Find Full Text PDFPLoS One
January 2025
Facultad de Biológicas, Instituto de Biotecnología y Biomedicina (BIOTECMED), Universitat de València, Burjassot, Spain.
The budding yeast Xrn1 protein shuttles between the nucleus, where it stimulates transcription, and the cytoplasm, where it executes the major cytoplasmic mRNA decay. In the cytoplasm, apart from catalyzing 5'→3' decay onto non translated mRNAs, Xrn1 can follow the last translating ribosome to degrade the decapped mRNA template, a process known as "cotranslational mRNA decay". We have previously observed that the import of Xrn1 to the nucleus is required for efficient cytoplasmic mRNA decay.
View Article and Find Full Text PDFPLoS Genet
January 2025
Biomedical Science Graduate Program, University of California San Diego, San Diego, California, United States of America.
Proteins with nuclear localization sequences (NLSs) are directed into the cell nucleus through interactions between the NLS and importin proteins. NLSs are generally short motifs rich in basic amino acids; however, identifying NLSs can be challenging due to the lack of a universally conserved sequence. In this study, we characterized the sequence specificity of an essential and conserved NLS in Mcm3, a subunit of the replicative DNA helicase.
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