Figure 4.

Composition and comparison of P+1 pockets. The pocket composition for PKA, MAPK, and CK2α and preferred amino acids in the P+1 position of their substrates are from Songyang et al. (1996). The assignment of amino acids that form the P+1 pockets for SRPK1 and 2 is based on the sequence alignment shown in Fig. 1 B, and the selected amino acids for SRPK2 are from Fig. 3 B. The deduced P+1 pocket for Clk/Sty is also based on a similar sequence alignment with kinases whose tertiary structures have been determined (not shown). The subdomain locations of individual amino acids in the P+1 pocket and their positions corresponding to those of PKA are indicated.