Fig. 4
![Fig. 4](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs12900-017-0079-7/MediaObjects/12900_2017_79_Fig4_HTML.gif)
Solvent-accessible surface area (SASA) of the three MTAP proteins and potential binding sites. a The Electrostatic Potential (EP) projected on proteins SASA is presented in red-white-blue color gradient for negatively, neutral and positively charged regions, respectively. The range of its variation is also presented. b Four binding sites (BSs) were identified by SOM-BSfinder on the SASA of the three MTAPs, each having a different surface color (pink, cyan, or green). They were ranked and colored according to descending cluster size from blue (highest neuron density associated with low U-values) to green, yellow and red (lowest neuron density associated with high U-values). The panels represent: (1) HuMTAP, (2) LiMTAP and (3) TbMTAP