CD36 Is Palmitoylated on Both N- and C-terminal Cytoplasmic Tails

Abstract

The membrane protein CD36 has been reported to carry out a wide range of potential functions, including serving as a receptor for thrombospondin, collagen, oxidized low density lipoprotein, fatty acids, anionic phospholipids, and Plasmodium falciparum malaria parasitized erythrocytes. This implicates CD36 in cellular adhesion, human atherosclerotic lesion formation, lipid metabolism, and malaria. A presumed rat homolog of CD36 was previously reported to be palmitoylated. We confirmed that human CD36 is palmitoylated and identified cysteines 3, 7, 464, and 466 as the palmitoylation sites using a mutagenesis approach. This result suggests that both the N- and C-terminal tails of CD36 are cytoplasmic. Published models for the topology of CD36 have the C terminus located in the cytoplasm but differ as to whether the N terminus is cytoplasmic or extracellular. To address this question, a C-terminal truncation mutant of CD36 was made by introducing a stop codon just upstream of the C-terminal transmembrane domain. This mutant was found membrane-bound when expressed in human embryonic kidney 293 cells, indicating that the N-terminal hydrophobic domain serves as a transmembrane anchor, and thus supporting a CD36 topology with two transmembrane domains.

Ligand-induced growth and compaction of CD36 nanoclusters enriched in Fyn induces Fyn signaling

“…This was motivated by the fact that all four intracellular cysteine residues of CD36 are palmitoylated (Tao et al, 1996) and Fyn is myristoylated and doubly palmitoylated, which would increase their affinities for cholesterol-enriched nanodomains (Levental et al, 2010;Lingwood and Simons, 2010). For this analysis, we measured Fyn activation and enrichment at CD36 clusters following cholesterol removal from the plasma membrane with methyl-β-cyclodextrin (MβCD).…”

CD36: Implications in cardiovascular disease

“…The intracellular domains of CD36 are located on very short cytoplasmic tails: the N-terminal tail is probably the result of an uncleaved signal peptide. Both tails are characterized by a pair of cysteine residues that are palmitoylated (Jochen, & Hays, 1993,Tao, Wagner, & Lublin, 1996 and these are important in positioning CD36 in caveolae and lipid rafts. Both the Nterminal and the C-terminal cytoplasmic domains have been shown to be important for efficient plasma membrane CD36 expression (Gruarin, Thorne, Dorahy, Burns, Sitia, & Alessio,.…”

Importance of the carboxyl terminus of FAT/CD36 for plasma membrane localization and function in long-chain fatty acid uptake

“…Like other class B scavenger receptors, such as scavenger receptor class B type I, FAT/CD36 is anchored in the plasma membrane by transmembrane domains at N and C termini and contains a large extracellular loop that is highly N-glycosylated (6)(7)(8). Human FAT/CD36 is palmitoylated at membrane-proximal cysteine residues in the Nand C-terminal cytoplasmic tails, and it is thought that this lipidation may serve to target and/or strengthen the attachment of the molecule to the plasma membrane (7).…”

“…Human FAT/CD36 is palmitoylated at membrane-proximal cysteine residues in the Nand C-terminal cytoplasmic tails, and it is thought that this lipidation may serve to target and/or strengthen the attachment of the molecule to the plasma membrane (7). Furthermore, because palmitoylation is reversible, it may regulate the translocation of FAT/CD36 between intracellular sites and the plasma membrane.…”