How does the clathrin-coated vesicle neck narrow? In the final stages of clathrin-coated vesicle (CCV) formation, Phosphatidylinositol-4,5-bisphosphate (PIP2) undergoes a dephosphorylation by phosphatases such as synaptojanin 1 (Synj1) [1]. Not only does this inhibit PIP2’s signal transduction capabilities and ensures that the adaptor proteins [...]

What is the CLIC/GEEC Endocytosis pathway? The CLIC/GEEC (CG) pathway is a clathrin-independent endocytic pathway mediated by uncoated tubulovesicular primary carriers called clathrin-independent carriers (CLICs) which arise directly from the plasma membrane and later mature into tubular early endocytic compartments called Glycosylphosphotidylinositol- anchored protein [...]

What is Arf6-associated endocytosis? Arf6-associated endocytosis is a clathrin-independent, plasma membrane-endosomal recycling pathway, regulated by the Arf6 protein, which is a member of the Arf family of small GTPases [1]. In this pathway, Arf6 cycles between the inactive GDP-bound state and active GTP-bound state. [...]

What is Rho-dependent IL-2 receptor endocytosis? Internalization of transmembrane receptors was thought to occur exclusively via clathrin-mediated endocytosis (CME). However, the discovery of clathrin-independent endocytic routes, in particular, the pathway that mediates the internalization of the cytokine receptor interleukin-2 (IL-2R), raises into question the [...]

What is flotillin-associated endocytosis? Flotillins, which are proteins that localize to specific microdomains or lipid rafts in the plasma membrane, mediate a clathrin-independent endocytosis pathway that is regulated by the Src family tyrosine kinase Fyn [1], [2]. Flotillins are detergent insoluble and named for [...]

What is Fast Endophilin-Mediated Endocytosis (FEME)? FEME is a novel clathrin-independent endocytic pathway, regulated by the BAR domain protein endophilin, where tubulo-vesicular carriers form within seconds at the plasma membrane upon activation of specific G-protein coupled receptors (GPCRs) by their ligands, internalizing GPCRs and [...]

What is exocytosis? Exocytosis is defined as the transport and fusion of secretory vesicles with the plasma membrane and the extracellular space. There are three exocytosis pathways that deliver vesicles to the plasma membrane. Found in all cells, the constitutive secretory pathway operates continuously [...]

How does scission of the clathrin-coated vesicle occur? As mentioned, in mammalian CME the GTPase dynamin is believed to play important roles in invagination and clathrin-coated pit (CCP) maturation [1]. Its binding partners endophilin and amphiphysin, can also induce tubulation of the vesicles and [...]

How are clathrin-coated vesicles uncoated? Uncoating is the process by which clathrin is removed from clathrin-coated vesicles (CCVs). In mammals, this ATP dependent process is driven by the 70kDa molecular chaperone ‘Heat shock cognate protein’. Although the exact mechanics of clathrin disassembly remain unclear, [...]

How are clathrin-coated vesicles transported? Different cytoskeletal networks have been implicated in the transport of clathrin-coated vesicles (CCVs). In yeast, the actin cytoskeleton traffics dissociated CCVs [1], whilst in mammals the microtubule network transports is involved in the sorting of CCVs to distinct populations [...]

What is autophagy? Autophagy, meaning self-eating, is an intracellular degradation system wherein unwanted cargo, such as old or damaged organelles, unneeded proteins, as well as pathogenic agents, are digested and the macromolecular contents from the digestion are released back into the cytosol [1]. First [...]

What is caveolar endocytosis? Macropinocytosis or ‘cell drinking’ is a type of endocytosis that involves the nonspecific uptake of extracellular material, such as soluble molecules, nutrients, and antigens. First observed in 1931 by Warren Lewis while working on rat macrophages, macropinocytosis was described as [...]