Figure 2.

Sky1p is structurally and functionally related to the metazoan SRPK family. (A) Sequence comparison of the SRPK family members, including Sky1p (SGDID L0003941). The kinase domains are highly conserved, as indicated by the percentages of amino acids identical to those in SRPK1. C. elegans, Caenorhabditis elegans. (B) Shared substrate specificity between Sky1p and human SRPK1. Equal masses of purified forms (WT, wild-type; RG, RT, GS, and KS, mutant RS/SR dipeptides containing the indicated amino acid changes; ΔRS, RS domain deletion) of the human SR protein ASF/SF2 were phosphorylated with purified human SRPK1 (Upper) and glutathione S-transferase–Sky1p (Lower).