+
Related Flashcards
Cards In This Set
| Front | Back |
|
Wht are the various post translational modifications that can occur on proteins? (5)
|
-proteolytic cleavage-attachment of lipid anchors-glycosylation-phosphorylation-methylation
|
|
Post-translational modifications (PTMs)
|
Modifications made to proteins after they have been synthesized (most of the time), at the very least they are added co-translationally
|
|
PTMs alter protein structure and therefore_____
|
Alter protein function
|
|
For many proteins, maturation/activation requires:
|
Trimming the polypeptide chain at various places by proteases and peptidases
|
|
If no other PTM, all proteins at least undergo____. What does this tell us?
|
Cleavage of the terminal Met residue and therefore we know that proteolytic processing is universal
|
|
Pre-peptides
|
Proteins moved to ER begin with this signal (also called a signal peptide) and it is cleaved by the signal peptidase while the protein is being translated into the ER lumen
|
|
Pro-peptides
|
Anything other than a signal peptide that has to be removed from a protein so it is fully active. They can sometimes double as inhibitors that, once removed, activate the protein. They can also be responsible for folding
|
|
Pre-pro-protein
|
When a protein has both a pre- and pro-peptides. This is considered the unmodified form while these are both/all attached
|
|
Insulin is synthesized in the pancreas as ____
|
Preproinsulin
|
|
How is insulin stored in the pancreas and when/how is it released?
|
Its stored in its inactive form in secretory vesicles. When blood glucose rises to its threshold its released.
|
|
Pre-peptide of insulin means ____
|
The protein is on its way to the secretory vesicles for storage
|
|
C-peptide
|
Connects the A and B polypeptides of insulin so they can form the proper disulfide pairings and is critical for folding. It must be removed for insulin to become active or else it wont bind the insulin receptor.
|
|
Covalent modification of proteins happens to what part of the proteins
|
Amino acid side chains
|
|
Collagen alpha chains are synthesized with ______ in the beginning. THese are required for _____.
--what if these are not present? |
--N- and C-terminal pro-peptides (and pre-peptides)
--quick assembly of the 4ยบ coiled coil structure --much slower assembly of the protein if the proprotein isn't there |
|
When are the N- and C-terminal pro-peptides of collagen are removed when and by what?
|
After assembly of the tropocollagen molecule and removed by specific peptidases.
|
