Primary external reference:
Substitution of histidine residue with arginine at position 1047 in the kinase domain of PIK3CA is predicted, based on PIK3CA crystal structure, to change the conformation of the activation loop (Huang et al. 2007). The PI3K complex containing PIK3CA H1047R mutant is constitutively active, in the absence of growth factors (Zhao et al. 2005, Horn et al. 2008), but its activity may be additional boosted by binding of PIK3R1 regulatory subunit to phosphopeptides generated by activated receptor tyrosine kinases (Hon et al. 2011).