Interplay between palmitoylation and other posttranslational modifications DHHC proteins are clearly master regulators of intracellular palmitoylation reactions, and thioesterases (such as Apt1) may be equally important. However, are these enzymes the only means of regulating palmitoylation? In fact, there is evidence that palmitoylation/depalmitoylation dynamics can also be (1) Negatively charged phosphate group prevents palmitoylation of an adjacent cysteine by blocking membrane interaction. (2) Palmitoylation-mediated membrane association prevents access of protein kinases to an adjacent phosphorylation site. (3) Phosphorylation could alter the depalmitoylation rate of a neighboring cysteine, e.g., by increasing access to a thioesterase enzyme. (B) Phosphorylation of a soluble protein prevents palmitoylation by inhibiting transient membrane interaction. (C, 1) Possible regulatory effects of nitrosylation on palmitoylation. Nitrosylation may prevent palmitoylation by direct competition for cysteine residues. (2) It is also possible that nitrosylation could directly displace palmitate. Note that the examples shown do not illustrate the full range of effects that phosphorylation might have on palmitoylation and vice versa.