1.C.81.2.1
Integral membrane protein 2B, ITM2B or BRI2, of 266 aas and 1 TMS. Binds to and regulates the activity of GLUT9, a sugar/urate transporter (TC# 2.A.1.1.72).  ITM2B inhibits urate uptake, but stimulates its efflux (Mandal and Mount 2019). Hyperuricemia plays a critical causative role in gout, but has a protective effect in neurodegenerative disorders, including Alzheimer's disease. Genetic variation in the SLC2A9 gene, encoding GLUT9, exerts the largest single-gene effect on serum uric acid. It plays a regulatory role in the processing of the amyloid-beta A4 precursor protein (APP) and acts as an inhibitor of the amyloid-beta peptide aggregation and fibrils deposition. It also plays a role in the induction of neurite outgrowth and functions as a protease inhibitor by blocking access of secretases to APP cleavage sites.  It also facilitates glutamate transmission via both pre- and post-synaptic mechanisms (Yao et al. 2019). It is thus an anti-Alzhemer's disease protein (Matsuda and Senda 2019). The ITM2B interactome in the human retina has been studied (Wohlschlegel et al. 2021). The role of BRI2 in health and disease has been reviewed (Martins et al. 2021).