2 CD36 Protein
Human CD36 has a total length of 472 amino acids and a predicted molecular weight of 53 kd(Abumrad et al., 1993). Due to glycosylation, the actual molecular weight is 88 kd(Greenwalt et al., 1992). CD36 contains two phosphorylation sites and four palmitoylation sites, which are distributed at the terminals of NH2 and COOH, respectively. And two ubiquitination sites are also at the COOH terminal.
CD36 is a membrane protein that is synthesized in the polyribosome, then transfers to the endoplasmic reticulum and Golgi apparatus for further processing, finally transported by endosome to the cytomembrane(Glatz et al., 2016). Under the stimulation of insulin(Samovski et al., 2018) or contraction(Luiken et al., 2002), it moves to the lipid rafts of the cell membrane to facilitate LCFA uptake, which may be associated with activation of PI3K-Akt and AMP kinase (AMPK). CD36 not only locates in plasma membranes and endosomes, but also distributes on mitochondrial(Monaco et al., 2015), but its specific function on mitochondrial remains unclear. CD36 is a double transmembrane protein which can’t form a channel that allows for fatty acids transferring from outside to the inside(Pepino et al., 2014). Interestingly, the outer ring of CD36 contains a large hydrophobic cavity, which provides a docking site for fatty acids and other hydrophobic ligands(Gomez-Diaz et al., 2016), facilitating the proximity of hydrophobic ligands to the cell surface, thus promoting the transportation of fatty acids into the cell.