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. The exocyst complex is composed of SEC3, SEC5, SEC6, SEC8, SEC10, EXO70A1 and EXO84B. Interacts with EXO84B. Binds to EXO70H1 AND EXO70B2 (PubMed:21199889). Localized to globular structures in the perinuclear region. During cytokinesis, localizes to the nascent cell plate and later to the cell plate insertion site and along the post-cytokinetic wall. Shuttles from the cytoplasm to the exocyst-positive organelle (EXPO) in the presence of EXO70E2 (PubMed:24307681). Belongs to the SEC15 family.