PNNL

Abstract

While directional movement requires morphological polarization characterized by formation of a leading pseudopodium at the front and a trailing rear at the back, little is known about how protein networks are spatially integrated to regulate this process. Here, we utilize a unique pseudopodial purification system and quantitative proteomics and phosphoproteomics to map the spatial relationship of 3509 proteins and 228 distinct sites of phosphorylation in polarized cells. Networks of signaling proteins, metabolic pathways, actin regulatory proteins, and kinase-substrate cascades were found to partition to different poles of the cell including components of the Ras/ERK pathway. Also, several novel proteins were found to be differentially phosphorylated at the front or rear of polarized cells and to localize to distinct subcellular structures. Our findings provide insight into the spatial organization of signaling networks that control cell movement and provide a comprehensive profile of proteins and their sites of phosphorylation that control cell polarization.