How is clathrin recruited to the plasma membrane? Clathrin-mediated endocytosis is triggered by phosphatidylinositol-4,5-bisphosphate (PIP2) accumulation within the plasma membrane. PIP2 accumulates as a result of phosphoinositide catalysis by the lipid kinases, phosphatidylinositol-4-kinase (PI4K) and phosphatidylinositol-4-phosphate-5-kinase (PI4P5K) [1], [2] and hydrolysis by phosphatases. The [...]

How does the clathrin coated pit form? Adaptor proteins such as AP-2, AP180 and CALM (Clathrin-assembly lymphoid myeloid leukaemia protein), which accumulate within the lipid bilayer, are responsible for the recruitment of the triskelion shaped Clathrin trimer. This trimer does not interact with the [...]

How does invagination and maturation of the clathrin-coated vesicle occur? Clathrin-coated vesicle maturation incorporates the activities of a range of proteins. Actin, myosin and WASP all have important roles in the formation and stabilization of clathrin-coated pits (CCPs) [1][2][3]. Evidence also suggests that F-actin [...]

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 membrane curvature? Membrane curvature refers to the physical bending of membranes to accommodate various cell morphology changes as well as the formation of membrane-bound transport intermediates like spherical vesicles or tubules. As membranes are inelastic and resistant to spontaneous bending, membrane curvature [...]

What is Membrane Trafficking? Membrane trafficking encompasses the wide variety of processes that go into the movement of cargo (typically proteins, pathogens and other macromolecules) using membrane bound transport vesicles. This transport can take place within different organelles in the same cell, or across [...]

What is caveolar endocytosis? Caveolar endocytosis is a clathrin-independent endocytic process which involves bulb-shaped, 50-60nm plasma membrane invaginations called caveolae (or ‘little caves’). Caveolae formation is driven by integral membrane proteins called caveolins as well as peripheral membrane proteins called cavins (reviewed in [1]). [...]

What is clathrin-mediated endocytosis? Clathrin-mediated endocytosis (CME) is a vesicular transport event that facilitates the internalization and recycling of receptors engaged in a variety of processes, including signal transduction (G-protein and tyrosine kinase receptors), nutrient uptake and synaptic vesicle reformation [1]. Two classical examples [...]

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 [...]