Sandbox8999: Difference between revisions
From Proteopedia
Jump to navigationJump to search
No edit summary |
No edit summary |
||
| Line 22: | Line 22: | ||
The formation of most cellular vesicles are facilitated by coat-proteins like clathrin.<ref name ="johnson"> Johnson, G. T., & Goodsell, D. (2007). Molecule of the Month: Clathrin. [http://dx.doi.org/10.2210/rcsb_pdb/mom_2007_4 doi: 10.2210/rcsb_pdb/mom_2007_4]</ref> Endocytic events are initiated through the activity of the clathrin coat and adaptor proteins that select the “cargo” that will be carried into the cell in vesicles.10 Cells endocytose vesicles from the plasma membrane to perform housekeeping tasks such as taking up nutrients, importing signaling receptors, mediating immune responses, cleaning up cell debris, or providing a pathway for pathogens or toxins.<ref name="johnson" /> | The formation of most cellular vesicles are facilitated by coat-proteins like clathrin.<ref name ="johnson"> Johnson, G. T., & Goodsell, D. (2007). Molecule of the Month: Clathrin. [http://dx.doi.org/10.2210/rcsb_pdb/mom_2007_4 doi: 10.2210/rcsb_pdb/mom_2007_4]</ref> Endocytic events are initiated through the activity of the clathrin coat and adaptor proteins that select the “cargo” that will be carried into the cell in vesicles.10 Cells endocytose vesicles from the plasma membrane to perform housekeeping tasks such as taking up nutrients, importing signaling receptors, mediating immune responses, cleaning up cell debris, or providing a pathway for pathogens or toxins.<ref name="johnson" /> | ||
'''The Canonical and | '''The Canonical and Noncanonical Pathway''' | ||
The canonical clathrin pathway is referred to as the clathrin coated pits and the coated vesicles of endocytosis, whereas the noncanonical clathrin pathway is related to the clathrin-actin assembles of phagocytotic processes. <ref name="harrison" /> | The canonical clathrin pathway is referred to as the clathrin coated pits and the coated vesicles of endocytosis, whereas the noncanonical clathrin pathway is related to the clathrin-actin assembles of phagocytotic processes.<ref name="harrison" /> | ||
Classical endocytosis involving clathrin-coated pits and clathrin-coated vesicles is referred to as the canonical clathrin pathway. | Classical endocytosis involving clathrin-coated pits and clathrin-coated vesicles is referred to as the '''canonical clathrin pathway'''.<ref name="harrison" /> Canonical clathrin-dependent pathways involve the uptake of transferrin (Tf) by transferrin receptor (TfR) and the uptake of LDL by LDL receptors (LDLR).<ref name="harrison" /> Early studies showed that LDL epidermal growth factor (Tf) bound to their specific receptors could be endocytosed within the same vesicle.<ref name="harrison" /> The receptors for these molecules are composed of tails on their cytoplasmic side that contain sequences, which determine cargo sorting and also signal for clathrin to bind.<ref name="harrison" /> Clathrin then coats these vesicles and endocytosis occurs.<ref name="harrison" /> Other pathways, such as reuptake of neurotransmitters into the synaptic cleft, are seen to have similar mechanisms to canonical clathrin pathways.<ref name="harrison" /> | ||
The clathrin-actin | The '''noncanonical clathrin pathway''' refers to clathrin-actin assemblies, which form phagocytotic vesicles in response to invading bacterium.<ref name="harrison" /> Pathogen invasion into nonphagocytic cells result in the recruitment of clathrin.<ref name="harrison" /> These pathogens invade the cell through a process called the “zippering” mechanism, in which actin filaments are utilized to surround the pathogens with the host-cell membrane.<ref name="harrison" /> Actin recruitment requires the formation of clathrin patches and thus the clathrin-assembly forms.<ref name="harrison" /> Actin is not usually needed in classical endocytosis, but it is required when the size of the cargo in the forming vesicle is too large for the vesicle to close.<ref name="harrison" /> This association between actin and clathrin is unique to this pathway and distinguishes the noncanonical from the canonical pathway.<ref name="harrison" /> | ||
== Disease == | == Disease == | ||
