Palmitoyltransferase that catalyzes the addition of palmitate onto various protein substrates, such as CGAS, HRAS and LCK (PubMed:23034182, PubMed:27481942, PubMed:35438208). Acts as a negative regulator of the cGAS-STING pathway be mediating palmitoylation and inactivation of CGAS (PubMed:35438208). May also have a palmitoyltransferase activity toward the beta-2 adrenergic receptor/ADRB2 and therefore regulate G protein-coupled receptor signaling (PubMed:27481942). {ECO:0000269|PubMed:23034182, ECO:0000269|PubMed:27481942, ECO:0000269|PubMed:35438208}. This is the function of ZDHHC18 (zDHHC palmitoyltransferase 18, ENSG00000204160).