Ras Associated And Pleckstrin Homology Domains Containing Protein 1 (RAPH1)

The deduced 1,236-amino acid protein shares significant similarity with mouse Grb10. RT-PCR ELISA detected moderate to high RAPH1 expression in all adult and fetal tissues and specific brain regions examined, except lung. Highest expression was in brain. The PH domain of LPD specifically bound phosphatidylinositol 3,4-bisphosphate, which targeted the PH domain of LPD to ruffles in PDGF-treated rat fibroblasts. LPD overexpression increased lamellipodial protrusion velocity, an effect observed when VASP-related proteins are overexpressed or artificially targeted to the plasma membrane. Conversely, knockdown of mouse Lpd expression impaired lamellipodia formation in mouse melanoma cells, reduced velocity of residual lamellipodial protrusion, and decreased F-actin content.