What is the difference between the trithorax (TrxG) and polycomb (PcG) complexes of proteins?
A) TrxG proteins methylate lysine 27 on histone H3 while PcG complexes methylate lysine 4 on H3
B) Methylation of lysine at position 4 on H3 results in silencing of gene expression
C) TrxG complex proteins activate gene expression by methylating lysine 4 on H3, while PcG complex proteins repress gene expression by methylating lysine 27 on H3.
D) Methylation of H3 on lysine 27 can result in activation of transcription

Question

Quizplus · Accepted Answer

TrxG complex proteins activate gene expression by methylating lysine 4 on H3, while PcG complex proteins repress gene expression by methylating lysine 27 on H3. Therefore, option C is the only correct choice. Option A is incorrect because it has reversed the roles of TrxG and PcG complexes. Option B is incorrect because methylation of lysine 4 on H3 is associated with active transcription, not silencing. Option D is incorrect because methylation of lysine 27 on H3 is associated with gene repression, not activation.

What Is the Difference Between the Trithorax (TrxG) and Polycomb