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. 2015 Aug 17;100(10):E1308–E1318. doi: 10.1210/jc.2015-1800

Figure 1.

Figure 1.

α-Klotho isoforms, sequence, and Western blot. A, Structure of the two isoforms of α-Klotho. Isoform 1 represents the full-length protein and contains a signal sequence domain (SS), two homologous domains (KL1, KL2), a short transmembrane domain (TM), and a short cytoplasmic tail. Shown is the site of the epitope for the antibody used in our experiments: AA 800 to 900, KL2. This epitope is absent from Isoform 2, a soluble, secreted protein that arises from alternative RNA splicing and contains only AA 1–549, and where the terminal 15 residues are replaced by the sequence shown. B, The full-length α-Klotho protein sequence of 1012 AA is shown, with KL1 and KL2 shown in red and green respectively, and TM highlighted (black). The peptides giving rise to the PRM signature are also shown (bold typeface; common to isoforms 1 and 2, red; exclusive to full-length α-Klotho, isoform 1, blue). C and D, Western blot analysis of cell lysates (C) and tissues (D) supports the presence of the full-length α-Klotho. Full-length rh α-Klotho protein (rh-α-Klotho). EC, epithelial cells.