@article {49815, title = {Positive and strongly relaxed purifying selection drive the evolution of repeats in proteins}, journal = {Nature Communications}, volume = {7}, year = {2016}, month = {Jun-11-2017}, pages = {13570}, doi = {10.1038/ncomms13570}, url = {http://www.nature.com/doifinder/10.1038/ncomms13570}, author = {Persi, Erez and Wolf, Yuri I. and Koonin, Eugene V} }