The p110/niSH2 structure shows that the complex is a compact assembly of p110a and p85a
domains, (Fig. 1). The overall shape of the complex is triangular with the RBD at the tip and the iSH2
forming the elongated side at the bottom. The iSH2 interacts with several of the p110a domains, in
particular with the ABD and the C2 domains. The helical domain interacts with the ABD and RBD
domains and even more extensively with the kinase domain. These interactions are without doubt
important for the control of the activity of the enzyme.