Lac repressor is an example of the DNA-binding motif common to many prokaryotic regulatory proteins and is:
A) a homeobox.
B) a zinc finger.
C) a basic region-leucine finger.
D) a helix-turn-helix.
E) none of the above.

Question

Quizplus · Accepted Answer

Lac repressor is a prokaryotic regulatory protein that binds to specific DNA sequences to regulate the expression of genes. It contains a DNA-binding motif known as a helix-turn-helix (HTH), which is commonly found in other prokaryotic regulatory proteins. The HTH motif consists of two alpha helices connected by a turn, with the second helix fitting into the DNA major groove and making specific contacts with the DNA bases. Therefore, option D is the correct answer. Homeoboxes, zinc fingers, and basic region-leucine fingers are other types of DNA-binding motifs found in eukaryotic proteins.

Lac Repressor Is an Example of the DNA-Binding Motif Common