Poster: Protein targeting & vesicular trafficking

Abs # 655: Analysis of intranuclear mobility of a plant serine/arginine-rich protein using FRAP and FLIP

Presenter:	Ali, Gul S, gul.ali@colostate.edu
Authors	Ali, Gul S (A)   Reddy, ASN  (A)
Affiliations:	(A): Colorado State University

Pre-mRNA splicing, an essential step in the expression of most eukaryotic genes, takes place in a spliceosome that consists of a set of five small ribonucleoprotein particles (snRNPs) and a large number of non-snRNP splicing factors. The serine/arginine-rich (SR) proteins, a conserved family of non-snRNP proteins, function at multiple steps in the assembly of spliceosome in non-plant systems. We have previously shown that the intranuclear distribution of a plant-specific splicing factor (SR45) is regulated by the transcriptional and protein (de)phosphorylation activities of cells (Plant J 36:883-893, 2003). Using the photobleaching techniques, fluorescence recovery after photobleaching (FRAP) and fluorescence loss in photobleaching (FLIP), we show that the mobility of GFP-SR45 varies in different domains of nucleus. More importantly, using several inhibitors we demonstrate that the movement of GFP-SR45 is dependent upon the physiological state of cells. These novel observations are in contrast to the mobility of similar proteins in animals, indicating fundamental differences in the movement of plant and animal serine/arginine-rich proteins.