Sequence alignment of human kallikreins (panel A) and three-dimensional structure of PSA (panel B).

Abstract

<p>Sequence alignment (panel A) is built with those human kallikreins for which the three-dimensional structure is available at the Protein Data Bank. The protein sequences were obtained from the NCBI database (<a href="http://www.ncbi.nlm-nih.gov" target="_blank">http://www.ncbi.nlm-nih.gov</a>). The progressive multiple alignment of PSA (also named kallikrein 3; NCBI entry number: CAD30845.1), kallikrein 1 (also named tissue kallikrein; KLK1; NCBI entry number: AAH05313.1), kallikrein 2 (KLK2; NCBI entry number: AAF08276.1), kallikrein 4 (KLK4; NCBI entry number: AAD38019.1), kallikrein 6 (KLK6; NCBI entry number: AAP35498.1), kallikrein 7 (KLK7; NCBI entry number: NP_644806.1), and human plasma kallikrein (HPK; NCBI entry number: AAF79940.1) was performed by the Clustal-Omega program (<a href="http://www.ebi.ac.uk/Tools/msa/clustalo" target="_blank">http://www.ebi.ac.uk/Tools/msa/clustalo</a>). Only the trypsin-like serine protease domain of HPK has been aligned. The “*” symbol means that the residues are identical in all the aligned sequences; the ":" symbol indicate conserved substitutions, and the "." symbol means semi-conserved substitutions. The amino acid sequence of bovine chymotrypsinogen (BCTRP; NCBI entry number: 681083A) has been reported as the template. Three-dimensional structure of PSA (panel B). In both panels, the image was produced using UCSF Chimera molecular graphics package <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0102470#pone.0102470-Pettersen1" target="_blank">[26]</a>. The “kallikrein loop” is in yellow <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0102470#pone.0102470-Menez1" target="_blank">[24]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0102470#pone.0102470-Tang1" target="_blank">[27]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0102470#pone.0102470-Fernndez1" target="_blank">[28]</a>, amino acid residues forming the catalytic triad are in red, and amino acid residues affecting the pH dependence of the catalytic parameters are in cyan.</p