UAS regulates expression of the cDNA for the 'B' isoform (646 amino acids) of orion in which the CX[[3]]C motif is changed to CX[[4]]C, tagged at the C-terminus with 2x Tag:MYC.
Scer\GAL4Tab2-201Y/orionB.CX4C.UAS.Tag:MYC fails to rescue orion1