The helix-loop-helix (HLH)motif is often preceded by a stretch of highly ______ amino acids whose ______ charged side chains contact DNA and determine the transcription factor's sequence specificity.
A)basic, positively
B)basic, negatively
C)acidic, negatively
D)acidic, positively
E)hydrophobic, neutral

Question

Quizplus · Accepted Answer

The HLH motif is typically preceded by a stretch of basic amino acids (e.g. arginine, lysine) whose positively charged side chains interact with the negatively charged DNA backbone. This interaction helps determine the sequence specificity of the transcription factor.

The Helix-Loop-Helix (HLH)motif Is Often Preceded by a Stretch of Highly