Lysine fatty acylation is an important protein posttranslational modification but mammalian lysine fatty acyl transferases have remained unknown so far. Here the authors report that the human N-terminal glycine myristoyltransferases 1 and 2 catalyze the addition of myristoyl chains to specific lysine residues and show that they myristoylate ARF6 lysine 3, which explains the unusual membrane binding properties of ARF6.