Fig. 2. Porcine DSP post-translational modifications (PTMs).

Porcine DSP extends from the DSPP amino terminus at Ile¹⁶ and extends to Arg³⁹¹. The bar maps PTMs in the DSP region. Key : A short line marks a predicted glycosylation or phosphorylation site that has not been determined experimentally. An “x” indicates a predicted site that is not modified. Arrowheads mark known cleavage sites. The numbers 2 and 20 beside an arrowhead indicates that MMP-2 or MMP-20 make that cleavage, respectively. In the primary amino acid sequence of porcine DSP there are eight predicted N-linked glycosylation(N at positions 52, 82, 92, 150, 170, 176, 191 and 330) (green), four potential O-linked glycosylations (T at positions 214, 215, 228, and 279) (pink), and four potential glycan attachment sites (S at positions 232, 235, 253, and 265) (orange). We have demonstrated at the protein level that two of the potential N-linked sites (N⁹² and N¹⁷⁰) (green squares) are glycosylated, but one (N³³⁰) is not (black cross). Two of the four predicted O-linked glycosylation sites (T²¹⁴ and T²²⁸) are not glycosylated (black crosses), but one predicted site (T²¹⁵) and two unpredicted sites (T²³¹ and T³³¹) are O-glycosylated (pink squares) ; and two of the four potential glycan attachment sites (S²⁵³ and S²⁶⁵) (orange squares) are used, but other two (S²³² and S²³⁵) are not.