Nuclear localization and in vivo dynamics of a plant-specific serine/arginine-rich protein.
Serine/arginine-rich (SR) proteins in non-plant systems are known to play important roles in both constitutive and alternative splicing of pre-messenger RNAs (pre-mRNAs). Recently, we isolated a novel SR protein (SR45), which interacts with U1 snRNP 70K protein, a key protein involved in 5' splice site recognition. SR45 is found only in plants and is unique in having two SR domains separated by an RNA recognition motif (RRM). To study the localization and dynamics of SR45, we expressed it as a fusion to green fluorescent protein (GFP) in cultured cells and transgenic Arabidopsis plants. The SR45 is localized exclusively to nuclei. In interphase nuclei, GFP-SR45 was found both in speckles and nucleoplasm. The speckles exhibited intranuclear movements and changes in morphology. Inhibition of transcription and protein phosphorylation resulted in redistribution of SR45 to bigger speckles. The change in the number and morphology of speckles caused by inhibition of transcription was blocked by an inhibitor of phosphatases. These results indicate that transcription activity of the cell and protein (de)phosphorylation regulate the intranuclear distribution of SR45.
Ali
Gul Shad
GS
Department of Biology and Program in Cell and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA.
Golovkin
Maxim
M
Reddy
Anireddy S N
AS
D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D047428:Protein Kinase Inhibitors; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014158:Transcription, Genetic
D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D008164:Luminescent Proteins; D047428:Protein Kinase Inhibitors; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; C483303:SR45 protein, Arabidopsis; D049452:Green Fluorescent Proteins; D010749:Phosphoprotein Phosphatases