Fig. 3. Biophysical ambiguity prevents phenotype prediction.

a–c P_R expression when combining two mutations that affect either protein folding (Mutation A) or another biophysical parameter (Mutation B) but not both: dimerization (a), DNA binding (b) or tetramerization (c). Number (left) and range (right) of possible double mutant P_R phenotypes (left). d–f Examples showing how a mutation with a known phenotype combines with other mutations, leading to 1 to 4 possible double mutant P_R expression levels. g–i Number (left) and range (right) of double mutant P_RM expression levels when mutations can affect folding or another biophysical parameter. j–l Examples showing how a mutation with a known P_RM phenotype can combine with other mutations to result in many different P_RM phenotypes. m, n Maximum number (left) and range (right) of double mutant phenotypes when two mutations can each affect one of the indicated number of different biophysical properties. Horizontal lines denote the mean of the data points. n = 4, 6, 4 and 1, respectively, for the groups with number of possible biophysical parameters equal to 1, 2, 3 and 4. Source data are provided as a Source data file.