transcription factor

[amejiag]

Hello every one

I was asked with the study a Transcription Factor X, and the have mouse modified genetically, as KO/KO = homozygous knockout; KO/WT = one KO allele, one wild type allele; TAD/TAD = homozygous for deletion of the transactivation domain (TAD); TAD/WT = one allele with TAD deletion, one WT allele; TAD/KO = one allele with TAD deletion, one KO allele; DBD/DBD = homozygous for point mutation inactivating the DNA binding domain (DBD); TAD/DBD = one allele with TAD deletion, one allele with DBD mutation These mice show: KO/KO = no phenotype; KO/WT = no phenotype; TAD/TAD = dramatic phenotype; TAD/WT = mild phenotype; TAD/KO = dramatic phenotype; DBD/DBD = no phenotype; TAD/DBD = dramatic phenotype. 

my answer to a give a concept that explain mechanistically these observations, particularly the mild phenotype of mice with TAD/WT genotype, is: The TAD in the homozygous form affect the phenotype drastically, but in the case of the TAD/WT, the gene that affect the transcription factor X, produce mild phenotype because the WT allele can recuperate some of the functions of the phenotype, maybe because could have binding sites for transcription coregulators that re-establish the phenotipe in some way. The deletion of the sequence of the transactivation domain, TAD and the clear drastic phenotype means that the TAD play a physiological role for the transcription factor XYZ, how it is observed with the deletion of both TAD alleles, or one deletion and one knockout.

could some one to guide me to answer  better this question, I am not sure what means to give a concept. 

Thanks very much