serine/threonine-protein kinase SRPK1; SFRS protein kinase 1; serine/arginine-rich protein-specific kinase 1; SR-protein-specific kinase 1 (SRPK1)

Function: 1) role in regulatory network for splicing a) intranuclear distribution of splicing factors in interphase cells b) reorganization of nuclear speckles during mitosis 2) hyperphosphorylates RS domain-containing phosphoproteins such as SFRS1 & SFRS2 & ZRSR2 on Ser during metaphase, but at lower levels during interphase - locks onto SFRS1 to form a stable complex & phosphorylates the RS domain 3) may phosphorylate splicing factors in close vicinity to the nuclear matrix. 4) component of the toposome 5) activated by phosphorylation on Ser-51 & Ser-555 6) present in a seven component complex, the toposome, which separates entangled circular chromatin DNA during chromosome segregation Cofactor: Mg⁺² Structure: - belongs to the protein kinase superfamily, CMGC Ser/Thr protein kinase family - contains 1 protein kinase domain Compartment: cytoplasm. nucleus Alternative splicing: - named isoforms=2 - at least one insoform may be produced at very low levels due to a premature stop codon in the mRNA, leading to nonsense-mediated mRNA decay Expression: - isoform 2 - predominantly expressed in the testis - also present at lower levels in heart, ovary, small intestine, liver, kidney, pancreas & skeletal muscle - isoform 1 - expressed only in testis - expressed at lower levels than isoform 2 Pathology: - mediates HBV core protein phosphorylation, a prerequisite for pregenomic RNA encapsidation into viral capsids - interacts with HHV-1 ICP27 protein

Properties

SIZE: entity length = 655 aa MW = 74 kD COMPARTMENT: cytoplasm cell nucleus STATE: active state MOTIF: Ser phosphorylation site {S37} Ser phosphorylation site {S51} kinase domain SITE: 80-653 MOTIF: ATP-binding site NAME: ATP-binding site SITE: 86-94 ATP-binding site NAME: ATP-binding site SITE: 109-109 ATP-binding site NAME: ATP-binding site SITE: 166-168 aspartate residue {D213} Ser phosphorylation site {S309} Ser phosphorylation site {S311} Ser phosphorylation site {S555}

Database Correlations

OMIM 601939 UniProt Q96SB4 Pfam PF00069 Entrez Gene 6732 Kegg hsa:6732 ENZYME 2.7.11.1

References

UniProt :accession Q96SB4