Post Translational Modifications Flashcards
Name 8 PTMs
Prenylation
Myristoylation
Palmitoylation
Methylation
Acetylation
Phosphorylation
Glycosylation
Ubiquitination
What is protein phosphorylation?
The attachment of phosphate to a protein AA side chain(the reactive OH)
What AA undergo protein phosphorylation?
Serine, threonine, tyrosine
What are the functions of protein phosphorylation?
Activate/inhibits enzymes
Controls cell signaling cascades
Controls gene expression events
Protein-protein interactions
Activates receptors and ion channels
How does serine/threonine kinase aid phosphorylation?
ATP is converted into ADP and the released pi attaches to the OH group of serine/threonine
Describe how the receptor tyrosine kinase works
Kinase is stimulated by the signal timer binding to the tyrosine kinase receptor
Tyrosine is phosphorylated
Intracellular proteins propagate signal to the nucleus by binding to phospho-tyrosine docking sites
What are phosphorylation motifs?
The placement of specific AA in a sequence that allow phosphorylation to take place
What is the purpose of protein glycosylation?
To facilitate protein folding, stability, trafficking
Has a role in immunogenicity and cell-to-cell communication
What proteins mostly undergo glycosylation?
Plasma membrane proteins
What is protein glycosylation?
The attachment of sugar molecules to protein keypoints
What sugars are used in glycosylation?
Mannose
Sialic acid for red bloodcells - puts -ve charge and cells repel to prevent clotting
GalNAc (N-acetylglucosamine) - glucose with an acetyl group attached
How is the translocon relevant in glycosylation?
A signal sequence within a protein causes it to translocate to the ER
Signal opens the translocon protein is expelled from thenbosome to the ER
How is the Golgi apparatus relevant in glycosylation?
It is were the maturation takes place- grycosyration occurs as protein moves through the GA
The protein fuses with it as a vesicle from the rough ER synthesis
Describe n-linked glycosylation
Protein linked with a n-linked oligosacchande via the nitrogen (NH2 side chain) in. asparagine
Describe the o-linked glycosylation
Protein attached to the oxygen (OH) via o-glycosidic bonds of o-linked oligosacchardes
Of serine, threonine,tyrosine, hydroyproline
