N-terminal domain of the protein encoded by the Drosophila tweety gene and related proteins, a family of chloride ion channels.
The protein product of the Drosophila tweety (tty) gene is thought to form a trans-membrane protein with five membrane-spanning regions and a cytoplasmic C-terminus. This N-terminal domain contains the putative transmembrane spanning regions. Tweety has been suggested as a candidate for a large conductance chloride channel, both in vertebrate and insect cells. Three human homologs have been identified and designated TTYH1-3. TTYH2 has been associated with the progression of cancer, and Drosophila melanogaster tweety has been assumed to play a role in development. TTYH2, and TTYH3 bind to and are ubiquinated by Nedd4-2, a HECT type E3 ubiquitin ligase, which most likely plays a role in controlling the cellular levels of tweety family proteins.