Figure 5.8.5.

The top 10 threading templates used by I-TASSER. The Z-score, which has been widely used for estimating the significance and the quality of template alignments, equals the difference between the raw alignment score and the mean in units of standard deviation. However, since LOMETS contains templates from multiple threading programs where the Z-scores are not comparable between different programs, I-TASSER uses a normalized Z-score (highlighted by the orange box) to specify the quality of the template, which is defined as the Z-score divided by the program-specific Z-score cutoffs. Thus, a normalized Z-score >1 indicates an alignment with high confidence. In this example, because there are multiple templates with the normalized Z-score above 1, the target is categorized by I-TASSER as an ‘Easy’ target. The multiple alignments between the query and the templates are marked by the blue box, where the residue numbers of each template are available by clicking on the corresponding ‘Download’ link. It can be seen from the multiple sequence alignment that, except for a few residues at the N- and C- terminals of the query (i.e., aligned to gaps ‘-’), other residues are well aligned with templates. This usually indicates that there is a high level of conservation between the target and templates.