Updated FTP location. Cold stress is one of the major limiting factors for global crop production. For survival at low temperature, plants need to sense the temperature changes in the surrounding environment. How plants sense and respond to the earliest drop in temperature is still not clearly understood. The plasma membrane and its adjacent extracellular and cytoplasmic sites are the first checkpoints for sensing temperature changes and subsequent events such as signal generation and solute transport. To understand how plants respond to early cold exposure, we have used a mass spectrometry-based phosphoproteomic method to study temporal changes in protein phosphorylation events in Arabidopsis membranes during 5 to 60 min of cold exposure. Phosphoproteomic analysis was carried out by using the following process. Arabidopsis membrane fraction was extracted from leaves. Trypsin digestion and phosphopeptide enrichment by HAMMOC method were performed, then purified peptide sample was analyzed by TripleTOF5600 (AB-SCIEX).