Functions in signal transduction from heterotrimeric G protein-coupled receptors. Binds to membranes containing phosphatidylinositol 4,5-bisphosphate. Can bind DNA (in vitro). May contribute to the regulation of transcription in the nucleus. Could be involved in the hypothalamic regulation of body weight. Contribute to stimulation of phagocytosis of apoptotic retinal pigment epithelium (RPE) cells and macrophages (By similarity). Interacts with GNAQ. Interacts with TULP1. Binds phospholipid and is anchored to the plasma membrane through binding phosphatidylinositol 4,5-bisphosphate. Is released upon activation of phospholipase C. Translocates from the plasma membrane to the nucleus upon activation of guanine nucleotide-binding protein G(q) subunit alpha. Does not have a cleavable signal peptide and is secreted by a non-conventional pathway. Defects in Tub are the cause of maturity-onset obesity, insulin resistance and sensory deficits. Belongs to the TUB family.