Primary structural features of SR-like protein acinusS govern the phosphorylation mechanism by SRPK2.

SRPKs (serine/arginine protein kinases) are highly specific kinases that recognize and phosphorylate RS (Arg-Ser) dipeptide repeats. It has been shown previously that SRPK1 phosphorylates the RS domain of SRSF1 (serine/arginine splicing factor 1) at multiple sites using a directional and processive mechanism. Such ability to processively phosphorylate substrates is proposed to be an inherent characteristic of SRPKs.