試題詳解

20. GAL4 is a transcription activator in yeast which promotes expression of a group of genes. In the upstream of genes driven by GAL4, there are one or more copies of a related 17-bp sequence known as

To show that UASGAL is the GAL4 responsive element, one constructed a lacZ reporter as shown in (a) and showed that the expression of lacZ is activated in galactose media in wild-type cells but not in gal4 mutants. She also did another set of experiments, in which various mutant GAL4 molecules are are examined for their transcription activator activities. Which of the following conclusions can be drawn from her experiments?
(A) N terminal aal-74 is required for GAL4 binding to UAS sequence
(B) N terminal aal-74 is sufficient to bind to UAS sequence
(C) C terminal aa738-881 is required for GAL4 to activate lacZ expression
(D) the fusion protein composed of aal-74 and aa738-881 is sufficient to activate lacZ expression.
(E) aa75-737 is not dispensable for lacZ expression