Final answer:
SMRT does not have HAT activity, while PCAF, p160, CBP, and p300 do possess intrinsic histone acetyltransferase activity and are involved in chromatin remodeling and transcriptional regulation.
Step-by-step explanation:
The student has asked which of the following does NOT have HAT activity: A) SMRT, B) PCAF, C) p160, D) CPB, or E) p300. Histone acetyltransferases (HATs) are enzymes that acetylate conserved lysine amino acids on histone proteins by transferring an acetyl group from acetyl-CoA to form ε-N-acetyllysine. Among the options given, SMRT (Silencing Mediator of Retinoic Acid and Thyroid Hormone Receptor) does not possess intrinsic HAT activity. SMRT is actually a transcriptional co-repressor that can recruit histone deacetylases (HDACs) to promoter regions of genes, thereby leading to chromatin condensation and gene repression. In contrast, PCAF, p160, CBP (CREB Binding Protein), and p300 are all known to possess intrinsic HAT activity, playing a role in chromatin remodeling and transcriptional regulation by acetylating histones and other proteins.