12445 RD-Hom 4(167-277) A(194-277) A(97-138) A(97-167) 6 A(97-194) N595A 7890 A(619-723) HD 10 A(1-392) 11 A(1-277) 12 13 12 (1-194) 13 14 15 HA I I I I I A(1-97) Wt NK-2 PUC41-75hsp40 Bgal HD 0 50 100 150 200 Normalized % of P-gal activity Figure 1. Effect of deletion in NK-2 on its transcription regulatory functions. The rectangles identify the segments present. Sequences deleted are shown as open areas.
The protein NK2 is a transcriptional regulator that functions both as a repressor and activator. To map the two domains more precisely a research group introduced deletion mutations within the coding sequences and studied the effect of a mutation on the NK2 regulatory function. A reporter construct (b-gal activity measurement) was used to monitor gene expression (row 15). Expression in the absence of NK2 was set at 100% (row 15). Repression is
indicated by a significant reduction in expression (see row 14 for example) and activation is indicated by higher that 100% activity (e. g., row 11). The presence of the wild type NK2 led to near complete inhibition of expression (row 14). In the figure a deletion is shown as an open area and the residues deleted are indicated on the left (e.g., the row 13 mutant has a deletion of residues 1-97).
From the data presented in the Figur, answer the following questions.
a) Which region(s) of the protein is required for repression function?
b) Is the C-terminal end required for repression?
c) What is the minimum region needed for repression?
d) Is the region labelled ‘HD’ sufficient for activation?
e) What is the minimum region needed for activation?
(A region refers to an amino acid segment, e.g., aa 15-275)
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