PMEL and polycystic kidney disease: The corn snake PMEL protein is 713 amino acids (aa) long and comprises: an initial signalling peptide at the N-terminus (IP; aa 1–20), the core amyloid fragment (CAF; aa 152–227), the polycystic kidney disease domain (PKD; aa 238-299), the repeat domain (RPT; aa 306–510), the Kringle-like domain (KLD; aa 559–609), a transmembrane helix (TM; aa 638–660), and a cytoplasmic domain (cyto; aa 661–713)21,23–25 (Fig. 2d).