Novel SR-protein-specific kinase, SRPK2, disassembles nuclear speckles.
SR-protein-specific kinase 1 (SRPK1) is first identified as a specific kinase for SR splicing factors. By RT-PCR of a conserved kinase domain, novel SR-protein-specific kinase clones were isolated from mouse brain. The cloned cDNAs encode a 106 kDa protein (648 amino acids, 92% identical to human SRPK1) and a 120 kDa protein (681 amino acids, 58% identical to human SRPK1). Therefore, they were designated mSRPK1 and mSRPK2, respectively. Northern blotting revealed the ubiquitous expression of mSRPK1 in all tissues examined and the tissue-specific expression of mSRPK2 in testis, lung, and brain. Both kinases phosphorylated SF2/ASF, a member of SR proteins in vitro and the phosphopeptide mappings were identical, indicating that these kinases phosphorylate the same site of SF2/ASF. Overexpression of mSRPK2 caused disassembly of cotransfected SF2/ASF and endogenous SC35. Our results indicate that SRPK family members may regulate the disassembly of the SR proteins in a tissue-specific manner.
Kuroyanagi
N
N
Department of Anatomy, Nagoya University School of Medicine, Japan.
Onogi
H
H
Wakabayashi
T
T
Hagiwara
M
M
D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism; D019556:COS Cells; D003001:Cloning, Molecular; D015180:Electrophoresis, Gel, Two-Dimensional; D005455:Fluorescent Antibody Technique; D007150:Immunohistochemistry; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D010748:Phosphopeptides / Q000032:analysis; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry*; D012326:RNA Splicing / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D016415:Sequence Alignment; D017421:Sequence Analysis; D000068103:Serine-Arginine Splicing Factors; D014162:Transfection / Q000235:genetics
D009687:Nuclear Proteins; D010748:Phosphopeptides; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; C499372:SRSF2 protein, mouse; D000068103:Serine-Arginine Splicing Factors; C490215:Srpk1 protein, mouse; C484679:Srpk2 protein, mouse; D017346:Protein Serine-Threonine Kinases