May play a role in membrane trafficking. Binds 3 Ca(2+) ions per subunit. The ions are bound to the C2 domains. Interacts with TCB2 via its C-terminal domain. More enriched in the cortical endoplasmic reticulum (ER) that is closely apposed to the cell membrane than in the perinuclear ER or internal ER tubules that connect the nucleus to the cortical ER. The C-terminal C2 domain shows Ca(2+)-dependent phospholipid binding. It binds to phosphatidylserine, phosphatidylinositol and various phosphoinositides. The other C2 domains do not retain all 5 conserved Asp residues found in calcium-binding C2 domains. Present with 4280 molecules/cell in log phase SD medium. Belongs to the tricalbin family.