ADRB2 and retinitis pigmentosa: In the β2-AR, compensatory mutants designed to rescue the expression of S161V4.53 were unsuccessful but V114A3.33/S165V4.57 double mutant rescued the expression of S165V4.57, while in rhodopsin L119A3.34/A164V4.53 rescued the defect in chromophore formation caused by the retinitis pigmentosa mutant A164V4.53[17], [23].