Pleckstrin Homology Like Domain Family B, Member 2 (PHLDB2)

LL5-beta bound immobilized PtdIns(3,4,5)P3 and was released by free competing PtdIns(3,4,5)P3, but not by any other phosphoinositides tested. In the presence of serum, LL5-beta was expressed in the cytosol of transfected porcine aorta endothelial cells. However, serum starvation, low PtdIns(3,4,5)P3 levels, or expression of a PDGF-beta receptor (PDGFRB) mutant unable to activate PI3K activity led to redistribution of a significant proportion of LL5-beta to intracellular vesicles. PH domain mutants of LL5-beta could not bind PtdIns(3,4,5)P3 and were constitutively localized to vesicles. Increased PtdIns(3,4,5)P3 levels redirected LL5-beta primarily to the cytosol. High PtdIns(3,4,5)P3 levels due to PDGF stimulation resulted in association of LL5-beta with the plasma membrane. .