In
bioinformatics
Bioinformatics () is an interdisciplinary field of science that develops methods and Bioinformatics software, software tools for understanding biological data, especially when the data sets are large and complex. Bioinformatics uses biology, ...
, the template modeling score or TM-score is a measure of similarity between two
protein structure
Protein structure is the three-dimensional arrangement of atoms in an amino acid-chain molecule. Proteins are polymers specifically polypeptides formed from sequences of amino acids, which are the monomers of the polymer. A single amino acid ...
s. The TM-score is intended as a more accurate measure of the global similarity of full-length protein structures than the often used
RMSD
The root mean square deviation (RMSD) or root mean square error (RMSE) is either one of two closely related and frequently used measures of the differences between true or predicted values on the one hand and observed values or an estimator on th ...
measure. The TM-score indicates the similarity between two structures by a score between
, where 1 indicates a perfect match between two structures (thus the higher the better).
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.
A quantitative study
shows that proteins of TM-score = 0.5 have a
posterior probability
The posterior probability is a type of conditional probability that results from updating the prior probability with information summarized by the likelihood via an application of Bayes' rule. From an epistemological perspective, the posteri ...
of 37% in the same
CATH Cath may refer to:
__NOTOC__ People
* Cath Bishop (born 1971), British former rower and 2003 world champion
* Cath Carroll (born 1960), British musician and music journalist
* Cath Coffey (), one of the earliest members of British rap band Stereo ...
topology family and of 13% in the same
SCOP
A ( or ) was a poet as represented in Old English poetry. The scop is the Old English counterpart of the Old Norse ', with the important difference that "skald" was applied to historical persons, and scop is used, for the most part, to designat ...
fold family. The probabilities increase rapidly when TM-score > 0.5. The TM-score is designed to be independent of protein lengths.
The TM-score equation
TM-score between two protein structures (e.g., a template structure and a target structure) is defined by
: