Promotes functional cell surface expression of the bitter taste receptors TAS2R16 and TAS2R43. Interacts with TAS2R16. Expressed predominantly in adult liver (PubMed:11896456, PubMed:17693185). Expressed in testis (PubMed:16720576, PubMed:17693185). Also expressed in kidney, lung and fetal liver (PubMed:17693185). Low levels in heart, thyroid, adrenal gland, pancreas, ovary, prostate, skin, plasma leukocytes, bone marrow and fetal brain (PubMed:17693185). Not detected in brain, spleen, colon, small intestine, skeletal muscle, stomach, placenta, salivary gland and uterus (PubMed:17693185). Belongs to the TMEM7 family.