TTYH1 is a member of the tweety family of proteins, a family of chloride anion channels containing five transmembrane regions. TTYH1 is a Ca2+-independent, volume-sensitive large conductance chloride (Cl-) channel. TTYH1 is primarily expressed in neural tissue and upregulated in astrocytoma, glioma, and several other cancers. Recent experiments have shown that TTYH1 is an integral endoplasmic reticulum (ER) membrane protein involved in cell proliferation and is thoμght to play an essential role in embryonic cell growth, possibly throμgh the Ca2+ storage/release process in ER membranes during early development.