Crustacean High Density Lipoprotein/beta-Glucan Binding Protein (HDL/BGBP) has been studied due to its role in nutrition and immune response via activation of the defense cells (hemocytes) upon binding 1,3-D-beta-glucan carbohydrates. In this study, HDL/BGBP was found to be composed mainly of beta sheets, as determined by circular dichroism. Lipoprotein aggregation resulted when HDL/BGBP interacted with phospolipid vesicles, laminaribiose (1,3-beta-glucan disaccharide) or heparin. HDL/BGBP has similar dissociation constants for laminaribiose (K(d)=22 mM) or heparin (K(d)=46 mM) as determined by 90 degrees light scattering.