The interaction between cell surface heparan sulphate and diffusible ligands such as FGFs is of vital importance for downstream signaling, however, there are few techniques that can be used to investigate this binding event. The ligand and carbohydrate engagement (LACE) assay is a powerful tool which can be used to probe the molecular interaction between heparan sulphate and diffusible ligands and can detect changes in binding that may occur following genetic or pharmacological intervention. In this protocol we describe an FGF17:FGFR1 LACE assay performed on embryonic mouse brain tissue. We also describe the method we have used to quantify changes in fluorescent LACE signal in response to altered HS sulphation.

Lipid droplets store triacylglycerols (triglycerides) and sterol esters to regulate lipid and energy homeostasis. Triacylglycerol measurement is often performed during the investigation of lipid droplet formation and growth. This protocol describes a reliable method using a fluorometric lipid quantification kit to measure triacylglycerols extracted from HeLa cells, which were treated with oleic acid to trigger the formation of lipid droplets. The lipid quantification kit employs a lipid-binding molecule that emits bright fluorescence only when bound to extracted triacylglycerols, whose content can be quantified by a simple fluorescence readout.