A number of eukaryotic acetyltransferases can be, on the basis of sequence similarities, grouped together into a family. These enzymes are:

• Choline o-acetyltransferase (EC 2.3.1.6) (ChoAcTase), an enzyme that catalyzes the biosynthesis of the neurotransmitter acetylcholine [1].
• Carnitine o-acetyltransferase (EC 2.3.1.7) [2].
• Peroxisomal carnitine octanoyltransferase (EC 2.3.1.-) (COT), a fatty acid β-oxidation pathway enzyme which is involved in the transport of medium- chain acyl-coenzyme A's from peroxisome to mitochondria [3].
• Mitochondrial carnitine O-palmitoyltransferases I and II (EC 2.3.1.21) (CPT), enzymes involved in fatty acid metabolism and transport [4].
• Yeast hypothetical protein YER024w.
• Mycoplasma pneumoniae putative acetyltransferase C09_orf600.

These enzymes share many regions of sequence similarities. As signature patterns we selected two of these regions. The first one, located in the N-terminal section of these enzymes is characterized by the presence of three [LIVM]-P dipeptides. The second region, located in the central part of these enzymes is characterized by the conservation of a number of charged residues including an histidine which probably plays a crucial role in the catalytic mechanism [5].