It is interesting to note that the three central operators , galOE2 , OE3 and OE4 , which have higher affinity for GalS than GalR , all have A/T at positions 8 of the operators ( Fig. 1B ) which is also the case for the mglB and galS operators ( Weickert and Adhya , 1993a , b ) which are preferentially regulated by GalS .