MAPT and Alzheimer disease: Despite hypotheses on the origin of this PTM conflicting, besides putative succinyl transferases, a non-enzymatic process is considered a likely cause, therefore, being detailed for tau in the following.41,194 Recently, first insights into the succinylation of lysine residue 311 were revealed, demonstrating that succinylated lysine occurs in nine out of ten AD patient's brain samples, however, not in healthy controls.118 Specific succinylation of the PHF6 peptide at K311 accelerates aggregation, whereas modification of K280 in PHF6* does not aggregate under the same conditions.