FIGURE 1.

Phylogenetic tree of the transporters of SLC17 family and genomic organization of human NPT4 gene (SLC17A3). A, computer-based phylogenetic analysis of the identified members of SLC17 illustrates the high degree of homology among the VGLUT sequences, which are distinct from type I phosphate transporters (NPTs). Among the type I phosphate transporters, only NPT1 and NPT4 have high expression in kidney. B, the diagrams of two isoforms of SLC17A3 (NPT4). Two isoforms of NPT4 differ in one exon (lacking the fourth exon for short isoform; isoform 2), the long isoform consists of 13 exons, and the number of nucleotide bases of each exon are shown in the middle line between the diagrams of the two isoforms. ▼, translation start site; *, translation termination site.