Clathrin-coated vesicles (CCVs) are involved in fundamental intracellular transport pathways such as receptor-mediated endocytosis at the plasma membrane and the sorting of lysosomal enzymes at the trans-Golgi network (TGN). The formation of CCVs is a dynamic and complex process that is mediated and controlled by the coat protein clathrin and a battery of accessory proteins.Here I introduce a novel CCV-associated protein with a serine/threonine kinase homology domain, called CVAK104 (Coated-Vesicle-Associated-Kinase of 104 kDa). Although CVAK104 is capable of binding to ATP, sequence analysis of the kinase domain and data from in vitro kinase assays indicated that CVAK is catalytically inactive and can therefore be classified as a pseudokinase.This book presents the charactarization of this novel protein CVAK104. Using biochemical and cell biological methods like fluorescence microscopy and RNA-interference you find out that CVAK104 plays an important role in intracellular trafficking processes.Welcome to the world of electrifying protein science!