Figure 3.

The residues involved in the SDSD-associated SPINT2 mutations are conserved among the Kunitz domains present in different human proteins. The amino acid sequences of 27 Kunitz domains from 18 human proteins are aligned and compared with bovine pancreatic trypsin inhibitor (BPTI). The six cysteine residues involved in the three disulfide bonds (black or gray shadow), the two β strands (yellow), one α helix (blue) are indicated. The P1 site (red shadow), putative N-glycosylation site (blue letter), the residues mutated in SCSD patients (red arrow point and red letter) are also marked. The alignment was performed using MUSCLE. The 2D structures were obtained from UniProtKB (marked by ^*) or predicted by PROMALS3D.