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. Author manuscript; available in PMC: 2017 Jul 21.
Published in final edited form as: Mol Cell. 2016 Jul 7;63(2):218–228. doi: 10.1016/j.molcel.2016.05.034

Figure 7. Role of nuclear SRPK1 for SR protein phosphorylation and splicing.

Figure 7

A) SRPK1 is drawn into the nucleus through contacts with CLK1. The SRPK1-CLK1 complex releases the SR protein from CLK1 and promotes splicing activity through enhanced contacts with U1. B) Catalytic cycle for SR protein phosphorylation by the SRPK1-CLK1 complex. The complex is held together by interactions between the N-terminus of CLK1 and the kinase domain of SRPK1. SRPK1 is the primary catalyst that phosphorylates Arg-Ser repeats in a C-to-N-terminal direction and CLK1 primarily phosphorylates Ser-Pro dipeptides. SRPK1 induces SR protein release by prohibiting contacts with the RS domain.