The Endogenous Pathway
The endogenous pathway is used to present cellular peptide fragments on the cell surface on MHC class I molecules. If a virus had infected the cell, viral peptides would also be presented, allowing the immune system to recognize and kill the infected cell. Worn out proteins within the cell become ubiquitinated, marking them for proteasome degradation. Proteasomes break the protein up into peptides that include some around nine amino acids long (suitable for fitting within the peptide binding cleft of MHC class I molecules). Transporter associated with antigen presenting (TAP), a protein that spans the membrane of the rough endoplasmic reticulum, transports the peptides into the lumen of the rough endoplasmic reticulum (ER). Also within the rough ER, a series of chaperone proteins, including calnexin, calreticulin, ERp57, and Binding immunoglobulin protein (BiP) facilitates the proper folding of class I MHC and its association with β2 microglobulin. The partially folded MHC class I molecule then interacts with TAP via tapasin (the complete complex also contains calreticulin and Erp57 and, in mice, calnexin). Once the peptide is transported into the ER lumen it binds to the cleft of the awaiting MHC class I molecule, stabilizing the MHC and allowing it to be transported to the cell surface by the golgi apparatus.
Read more about this topic: Antigen Processing
Other articles related to "endogenous":
... Endogenous Depression was initially considered valuable as a means of diagnostic differentiation with Reactive depression ... Indeed, this view of endogenous depression is at the root of the popular view that mood disorders are a reflection of a 'chemical imbalance' in the brain ... More recent research has shown that the probability of an endogenous depression patient experiencing an adverse life event prior to a depressive episode is roughly ...
... referred to as opioid growth factor (OGF), is a naturally occurring, endogenous opioid peptide that has opioid effects of a relatively short duration ... are considered to be the primary endogenous ligands of the δ-opioid receptor, due to their high potency and selectivity for the site over the other ...
Famous quotes containing the word pathway:
“Many are obstinate with regard to the pathway once they have set upon it, few with regard to the goal.”
—Friedrich Nietzsche (18441900)