This hy??pothesis is supported by our experi??ments with LacI/GalR ho??mologs.4Using these proteins. we identified a class of important. non??con??ser??v??ed ami??no acid po??si??tions that does not fol??low any of the rules in Box 1. Our ongoing experiments show that predictions for substi??tu-tion out??comes have nearly zero power at these positions. We named this group ???rheostat positions???. after their most prominent cha??racteristic: When multiple amino acids were substituted at one rheostat position. functions of the mutant proteins could be rank-order??ed to show a pro??gressive effect (Fig. 1A. page 3).
Research Start Date