2.A.20.2.7
Na⁺-dependent phosphate transporter 1 (PiT-1). Gibbon ape leukemia virus receptor 1 (GLVR-1), Slc20A1 (K_M=24μM).  The protein has an experimentally tested 12 TMS topology (Farrell et al. 2009).  A knock-out mutation of the mouse orthologue results in abnormal endocytosis in the yolk sac visceral endoderm and embyonic death at the 12.5 day stage (Wallingford and Giachelli 2014). PiT1 levels are elevanted in somatotroph adenomas and are positively associated with tumor size, invasive behavior and tumor recurrence in somatotroph adenomas. It may be associated with the activation of the Wnt/betacatenin signaling pathway (Li et al. 2019).  The tails are important regulatory domains required for the endocytosis of the Rgt2 and Snf3 glucose sensing receptors triggered by different cellular stimuli (Xiao et al. 2024). Ehrlichia chaffeensis infects and proliferates inside monocytes and macrophages and causes human monocytic ehrlichiosis (HME), an emerging life-threatening tick-borne zoonosis. After internalization, E. chaffeensis resides in specialized membrane-bound inclusions, E. chaffeensis-containing vesicles (ECVs), to evade host cell innate immune responses and obtain nutrients (Li et al. 2024).  Host cells recognize E. chaffeensis Ech_1067, a penicillin-binding protein, and then upregulate the expression of PIT1, which transports phosphate from ECVs to the cytosol to inhibit bacterial growth.