# Template modeling score

In bioinformatics, the **template modeling score** or **TM-score** is a measure of similarity between two protein structures with different tertiary structures. The TM-score is intended as a more accurate measure of the quality of full-length protein structures than the often used RMSD and GDT measures. The TM-score indicates the difference between two structures by a score between , where 1 indicates a perfect match between two structures.^{[1]} Generally scores below 0.20 corresponds to randomly chosen unrelated proteins whereas structures with a score higher than 0.5 assume roughly the same fold.^{[2]}
A quantitative study
^{[3]}
shows that proteins of TM-score = 0.5 have a posterior probability of 37% in the same CATH topology family and of 13% in the same SCOP fold family. The probabilities increase rapidly when TM-score > 0.5. The TM-score is designed to be independent of protein lengths.

## The equation

where and are the lengths of the target protein and the aligned region respectively. is the distance between the th pair of residues and

is a distance scale that normalizes distances.

## See also

- RMSD — a different structure comparison measure
- GDT — a different structure comparison measure
- LCS — a different structure comparison measure

## References

## External links

- TM-score webserver — by the Yang Zhang research group. Calculates TM-score and supplies source code.