Essential sequential series#

There are 20 serines within the RS domain of ASF/SF2, of which SRPK1 processively phosphorylates nearly 12 series present within the N-terminal half of the RS domain (RS1 motif) ( Aubol et al., 2003 Velazquez-Dones et al., 2005). One of the well-studied SR proteins is ASF/SF2. SRPKs are highly RS-specific kinases and only phosphorylate serine (not threonine) residues that are located adjacent to arginines (not lysines) in their substrates ( Gui et al., 1994b Wang et al., 1998).

The SR protein kinase (SRPK) and Clk/Sty family of protein kinases predominantly phosphorylate SR proteins in vivo.

Several protein kinases have been reported to phosphorylate the RS domains of SR proteins ( Blaustein et al., 2005 Colwill et al., 1996 Gui et al., 1994a Rossi et al., 1996). Phosphorylation of SR proteins also dictates their nuclear import ( Lai et al., 2001), and some SR proteins have been shown to serve additional roles in mRNA export and translation regulation ( Huang et al., 2003, 2004 Sanford et al., 2004, 2005). For proper execution of splicing activity, cycles of phosphorylation and dephosphorylation of SR proteins are important ( Misteli et al., 1997 Shi et al., 2006a Xiao and Manley, 1997, 1998). SR proteins are extensively phosphorylated at their RS domains and can exist in differentially phosphorylated (hypo- and hyperphosphorylated) states ( Fu, 1995 Graveley, 2000). All SR proteins share a common structural organization the N terminus consists of one or two RNA-recognition motifs (RRMs), whereas the C terminus contains arginine/serine (RS) dipeptide repeats and is referred to as the RS domain ( Fu, 1995 Graveley, 2000). The SR proteins represent a family of splicing factors that are essential for both constitutive and alternative splicing and are highly conserved in metazoans and plants ( Birney et al., 1993 Black, 2003 Blencowe, 2000).

Essential sequential