Fig. 2

Classification of transporter types and cell populations for urate handling. A Schematic diagram of four types of urate transporters classified based on their subcellular localization and physiological roles (apical/basolateral and influx/efflux). The eight transporters were classified into one of the following four transporter types: (1) SLC22A11 and SLC22A12 as Apical Influx (AI) transporters; (2) SLC17A1 and SLC17A3 as Apical Efflux (AE) transporters; (3) SLC22A6, SLC22A7, and SLC22A8 as Basolateral Influx (BI) transporters; or (4) SLC2A9 as Basolateral Efflux (BE) transporter. The cooperation of an AI transporter and a BE transporter leads to urate reabsorption (red). The cooperation of a BI transporter and an AE transporter leads to urate secretion (blue). B Venn diagram indicating cell populations, which were classified based on the positivity of influx transporters. Cell clusters in the PT and DL were classified into one of the following cell populations: AI transporter—Positive (AIP) cell population, BI transporter—Positive (BIP) cell population, Dual Influx transporter—Positive (DIP) cell population, or Dual Influx transporter—Negative (DIN) cell population. C, D Bar plots indicating the percentage (y-axis) of AI transporters (C) and BI transporters (D) in the DIP cell population across the regions (x-axis) in the DIP cell population. E Scheme of expression pattern of influx transporters. The apical membrane is to the left of the cells and the basolateral membrane is to the right of the cells. Red symbols represent the AI transporters, which are only single kind expressed in single cells. Blue symbols represent the BI transporters, which are single or multiple kind(s) expressed in single cells. Arrows indicate directions of urate flow