Serine/arginine-rich protein-specific kinases are a small family of serine/threonine protein kinases that phosphorylates serine residues in sequence regions containing repetitive serine/arginine-rich dipeptides. There are three known family members, of which SRPK1 and SRPK2 are the most well-studied. Multiple research studies have shown these kinases play an important role in post-transcriptional regulation, notably via phosphorylation of SR-family RNA splicing factors. SRPK2 has also been implicated in lipid biogenesis, following activation through sequential phosphorylation by mTORC-activated S6K1 and casein kinase 1. Phosphorylation of SRPK2 at Ser494 and Ser497 promotes nuclear translocation of SRPK2, thereby enabling its regulation of mRNA splicing factors involved in lipid biogenesis. Notably, SRPK1 and SRPK2 have both been implicated in the phosphorylation of key viral proteins, including the nucleocapsid protein of the SARS and SARS-CoV-2 coronaviruses, a modification that may be essential for viral replication.
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