Searching the extracellular domain of CD36 for fatty acid binding by Surface Plasmon Resonance

Abstract

Obesity has become a major public health concern and represents a predisposition factor for the development of cardiovascular‐related disease, ischemic stroke, and non‐insulin dependent diabetes mellitus. Deciphering the molecular mechanisms of ligand binding and subsequent signaling of plasma membrane “scavenger” proteins such as CD36, will provide new insights for therapeutic interventions for lipotoxicity, inflammation, and disease associated with obesity. Upon CD36 ligand binding and activation, inflammatory signaling often occurs, leading to an increase in proinflammatory cytokines. Localized fatty acid (FA) binding at the plasma membrane has been postulated to occur in a single site in the extracellular‐loop of the two‐pass transmembrane receptor CD36, which is also a well‐established oxLDL binding domain. FA binding to CD36 has been poorly characterized; furthermore, lower affinity binding sites might be present in the large, glycosylated domain. Here we report novel studies of FA binding to CD36 by the biophysical method Surface Plasmon Resonance (SPR). After covalently linking CD36 to an SPR chip surface, various aqueous FA's were pulsed across the surface for a time period of 60s. For comparison, human serum albumin (HSA) was studied in parallel experiments. This method detected FA binding to CD36 at a lower capacity than to HSA, but with similar rapid association and dissociation.