Lipid-binding tricalbin; one of at least 7 proteins (Ice2p, Ist2p, Scs2/Scs22p, Tcb1-Tcb3p) that affect cER tethering and contact with the plasma membrane (PM); regulates PI4P levels by controlling access of the phosphatase Sac1p to its PM substrate PI4P; regulates PM phospholipid homeostasis; contains 3 calcium and lipid-binding domains; localizes to the cortical ER and mitochondria; localizes to the nucleus-vacuole junction during glucose restriction; C-termini of Tcb2p and Tcb3p interact