Acetylation

Acetylation (or in IUPAC nomenclature ethanoylation) describes a reaction that introduces an acetyl functional group into an organic compound. Deacetylation is the removal of the acetyl group.

Moreover, it is that process of introducing an acetyl group into a compound, specifically, the substitution of an acetyl group for an active hydrogen atom. A reaction involving the replacement of the hydrogen atom of a hydroxyl group with an acetyl group (CH3 CO) yields a specific ester, the acetate. Acetic anhydride is commonly used as an acetylating agent reacting with free hydroxyl groups.

Acetylation of proteins
In biology, i.e. in living cells, acetylation occurs as a post-translational modification of proteins, for example, histones and tubulins.

Histone Acetylation and Deacetylation
In histone acetylation and deacetylation, the histones are acetylated and deacetylated on lysine residues in the N-terminal tail as part of gene regulation.

Typically, these reactions are catalyzed by enzymes with "histone acetyltransferase" (HAt) or "histone deacetylase" (HDAc) activity.

Tubulin Acetylation and Deacetylation
Tubulin Acetylation and Deacetylation system is well worked out in Chlamydomonas. A Tubulin acetyltransferase located in the axoneme acetylates a specific lysine residue in the α-tubulin subunit in assembled microtubule. Once disassembled, this acetylation can be removed by another specific deacetylase which is cytosolic. Thus the axonemal microtubules (long half life) carry this signature acetylation absent from cytosolic microtubules (short half life).