This is the N-terminal domain of fungal and eukaryotic Sec3 proteins. Sec3 is a component of the exocyst complex that is involved in the docking of exocytic vesicles with fusion sites on the plasma membrane.This N-terminal domain contains a cryptic pleckstrin homology (PH) fold, and all six positively charged lysine and arginine residues in the PH domain predicted to bind the PIP2 head group are conserved. The exocyst complex is essential for many exocytic events, by tethering vesicles at the plasma membrane for fusion. In fission yeast, polarised exocytosis for growth relies on the combined action of the exocyst at cell poles and myosin-driven transport along actin cables [1].

1: Fission yeast sec3 and exo70 are transported on actin cables and localize the exocyst complex to cell poles. Bendezu FO, Vincenzetti V, Martin SG; PLoS One. 2012;7:e40248. PMID:22768263