Component of the exocyst complex involved in the docking of exocytic vesicles with fusion sites on the plasma membrane during regulated or polarized secretion. Involved in polarized cell growth and organ morphogenesis. During cytokinesis, involved in cell plate initiation, cell plate maturation and formation of new primary cell wall. Probable component of an exocyst subcomplex specifically involved in autophagy-related, Golgi-independent membrane traffic to the vacuole. Regulates autophagosome formation and autophagy-related Golgi-independent import into the vacuole. The exocyst complex is composed of SEC3, SEC5, SEC6, SEC8, SEC10, EXO70A1 and EXO84B. Interacts with SEC3A and EXO70B1. Binds to EXO70H1 AND EXO70B2 (PubMed:21199889). Localized to globular structures in the perinuclear region (PubMed:19895414). Shuttles from the cytoplasm to the exocyst-positive organelle (EXPO) in the presence of EXO70E2 (PubMed:24307681). No visible phenotype under normal growth conditions, but the double mutant sec5a-1 and sec5b-1 is male gametophytic lethal due to defect in pollen germination and pollen tube growth. Belongs to the SEC5 family.