sequence of amino acids. Isoform 2 Isoform 2 is different from isoform 1, as the sequence of amino acids 1-12 is missing and the sequence from the 13th to the 36th amino acid is charged by the following: MWLTWPFCFLTITLREEGVCHLES Isoform 3 Is quite similar to the canonical sequence, the only differences is that the sequence of amino acids in 195th-218th position (RPPAPSLRATRHSRAAAVDPTPAA) is substituted by proline (P). Isoform 4 Isoform 4 is different to the canonical sequence as the sequence of amino acids 323-333 from the canonical chain (RGTPPGLVAQS) has been substituted by a different sequence (SSLPRSEESRY). Additionally, the sequence of amino acids 334-421 is missing. Isoform 5 In this case, isoform 5 differs to the canonical sequence as the sequence of amino acids 324-421 has been eliminated. Isoform 6 Isoform 6 is probably the isoform which differs the most from the canonical sequence. The sequence of amino acids 195-218 (RPPAPSLRATRHSRAAAVDPTPAA) is substituted by proline (P), just like in the isoform 3; the sequence 323-333 (RGTPPGLVAQS) is changed by (SSLPRSEESRY) and the sequence of amino acids 334-421 is missing, just like in isoform 4. Isoform 7 The difference between isoform 7 and the canonical sequence is that the sequence of amino acids in 195th-218th positions (RPPAPSLRATRHSRAAAVDPTPAA) has been changed by proline (P) and also the sequence 334-421 is missing. Molecular function Microtubules are highly dynamic tubular polymers assembled from protofilaments of α/β-tubulin dimers, and are essential for intracellular transport, architectural organization, cell division, cellular morphogenesis and force production in eukaryotic cells. There is a constant modulation of the balance between dynamic short-lived, and stable long-lived microtubule subpopulations in the cell. Although microtubules usually function as dynamic polymers, for some specific functions they require more stability. The acetylation is used y the cell as a marker for these stable microtubules. ATAT1 specifically acetylates ‘Lys-40’ in alpha tubulin on the lumenal side of microtubules. This is the only known posttranslational modification in the microtubule lumen, but it is still unknown how does the enzyme access the lumen. The two substrates for this enzyme are Acetyl-CoA and α-tubulin-L-lysine. Despite its similarity to other acetylating enzymes, it catalyses exclusively the tubulin acetylation reaction. This catalysis occurs when the Acetyl-CoA molecule attached to the enzyme transfers its Acetyl group to the lysine. This is the reaction catalyzed by ATAT1: Acetyl-CoA + [alpha-tubulin]-L-lysine CoA + [alpha-tubulin]-N6-acetyl-L-lysine Several experiments concluded that the acetylation is more efficient in