Protein Modifications Flashcards
Why does the Golgi receive material from endosomes and secretory vesicles
So it doesn’t get depleted of resources
What does proteolysis modification allow
Many isoforms from a single mRNA
Conversion to an active form
Enhancement of proper folding
Enhancement of insertion of the protein into membranes
What does covalent addition protein modification allow
Control of interaction with other proteins
Enhance stability/degradation
Enhance transport
Activation/inactivation
What happens if the machinery for the removal of signal sequences is faulty
The accumulation of immature proteins in the membrane
What determines the eventual location of a protein
Intraprotein signal sequences
What determines whether an intramembrane protein should be single or multipass
The location of the stop- and start- transfer sequences in the protein
Where is insulin initially produced and in what form
Beta cells in the Islet of Langerhans of the pancreas
Preproinsulin
Where is preproinsulin proteolyzed into proinsulin
Endoplasmic Reticulum
Where is proinsulin proteolyzed into insulin
Golgi
What is removed during proteolysis
Signal sequences and unnecessary chains
What are nucleosomes made of
Histone octamers
Explain how acetylation of histones exposes DNA
The acetyl groups are negatively charged and so is DNA. The addition of acetyl group to lysine 4 of histone 3 causes the histone to be negative and repel the DNA
Explain how methylation of histones inactivates a gene
Methyl groups are positively charged and DNA is negatively charged. The addition of methyl group increases the attraction between the two causing DNA to compact into nucleosomes
Describe how protein functionality is turned on and off
?
Ubiquitin is positive due to being rich in which residue
Lysine
