Milk lipid globules: control of their size distribution.

Micro lipid droplets fuse with each other in vivo to form larger precursors of milk lipid globules. The extent of fusion dictates the size range of lipid globules in milk. A cell-free system in which micro lipid droplet fusion can be induced has been developed. Fusion was promoted by calcium and a protein complex from cytosol. Exogenously supplied gangliosides were potent fusion-promoting agents. Endogenous gangliosides were detected on micro lipid droplet surfaces by immunocytochemical localization. Monoclonal antibody to disialyllactosylceramide (GD3) inhibited micro lipid droplet fusion. These observations are suggestive of a role for gangliosides in micro lipid droplet fusion in situ.