Sphingomyelin synthase 2 is palmitoylated at the COOH-terminal tail, which is involved in its localization in plasma membranes.
Sphingomyelin synthase (SMS) is an enzyme that catalyzes the transfer of phosphocholine from phosphatidylcholine to ceramide for sphingomyelin synthesis. Here, we show that SMS2 is palmitoylated at cysteine residues via thioester bonds in the COOH-terminal cytoplasmic tail. [3H]palmitic acid labeling of SMS1 or SMS2-overexpressing HEK293 cells revealed that SMS2, but not SMS1, is palmitoylated. Site-directed mutagenesis of cysteine residues to alanine ones indicated that the COOH-terminal cysteine cluster of the enzyme is palmitoylated. Mutation of all potential palmitoylation sites resulted in a dramatic reduction in the plasma membrane distribution of SMS2, whereas it did not affect the in vitro enzyme activity. These results suggested that this posttranslational modification is important for determination of the subcellular localization of SMS2.
Tani
Motohiro
M
Department of Chemistry, Faculty of Sciences, Kyushu University, 6-10-1, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan. tani@chem.kyushu-univ.jp
Kuge
Osamu
O
D000595:Amino Acid Sequence; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology*; D003545:Cysteine / Q000235:genetics / Q000378:metabolism; D006801:Humans; D054878:Lipoylation; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D017855:Transferases (Other Substituted Phosphate Groups) / Q000235:genetics / Q000378:metabolism*
D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C455440:SGMS1 protein, human; D017855:Transferases (Other Substituted Phosphate Groups); D003545:Cysteine