Advances in dairy Research
Open Access

Phosphoproteomics of milk lipid droplet proteins: New insights into lipid droplet secretion from the mammary epithelial cell

International Dairy Meet

June 29-30, 2016 New Orleans, USA

Christelle Cebo

University Paris-Saclay, France

Posters & Accepted Abstracts: J Adv Dairy Res

Abstract :

Lipid droplets are secreted into milk by a complex process which begins by burgeoning of lipids at the endoplasmic reticulum of the mammary epithelial cell (MEC). Lipid droplets enveloped by organelle-derived phospholipids reach the apical pole of the cell where they are wrapped by the plasma membrane to be secreted as fat globules into milk. Analyzing the fine protein composition of the Milk Fat Globule Membrane (MFGM), the triple-layered membrane surrounding milk lipid droplets can therefore provide mechanistic clues to better understand lipid droplet biosynthesis and secretion pathways. We combined a high sensitive Q Exactive LC-MS/MS analysis of MFGM-derived peptides with the use of an in-house database intended to improve protein identification in the goat species. Using this approach, we performed the identification of 442 functional groups of proteins in the MFGM from goat milk. To get a more comprehensive view of intracellular mechanisms driving lipid droplet dynamics in the MEC, we decided to investigate for the first time whether MFGM proteins were phosphorylated. A phosphopeptide enrichment approach let us pinpoint 271 sites of phosphorylation on 124 unique MFGM proteins. We are now investigating the putative role of these phosphosites with regard to lipid droplet biology by using site-directed mutagenesis studies in cellular models.

Biography :

Email: christelle.cebo@jouy.inra.fr