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

Question

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

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.