Fate of newly synthesized proteins Flashcards
Understand the role of new proteins, also how they are synthesized and where they can be sent in the cell. (23 cards)
What organelle is used to synthesis proteins?
Ribosomes
Proteins that are destined for membranes or lysosomes are synthesised by what type of Ribosome?
Membrane bound Ribosome
Name the first organelle required for protein synthesis
Nucleus
What happens (in terms of protein synthesis) in the nucleus?
Stretch of DNA is transcribed
mRNA leaves via the nuclear pores
What is the second organelle responsible for protein synthesis?
Rough Endoplasmic Recticulum
What occurs (in terms of protein synthesis) in the RER?
mRNA binds to ribosomes to be translated
The ribosome can be bound to RER or unbound.
The final organelle in protein synthesis is?
Golgi Apparatus
What occurs in terms of protein synthesis at the Golgi apparatus?
The protein undergoes further changes/ packaging for example, ubiquination / addition of sugars such as mannose-6-phosphate.
A vesicle full of the protein buds from the golgi where it is sent to its final destination.
The initial steps of glycosylation occur in what organelle?
Rough endoplasmic reticulum
What is the protein disulfide isomerase used for?
Help assist with the formation of disulphide bond
What is a folding chaperone?
a protein that assists with the folding of a protein into its tertiary structure.
Name one use in protein synthesis for the Smooth endoplasmic reticulum.
Modification of the newly synthesized protein, examples include addition of carbohydrate, phosphate and lipid groups.
“Pre”proinsulin is an example of what type of protein?
Signal recognition peptide.
What can increase the misfolding of proteins?
Exposure to elevated temperatures.
If a protein is tagged with a polymer of ubiquitin what does this mean?
This means they are will be sent to lysosomes for degradation by proteasomes found in the lysosome.
When vesicles bud onto the golgi what side for they join?
Cis face
Vesicular trafficking is regulated by what?
A specific coat of proteins on the vesicle and GTPases.
V snares are found where?
On the vesicle acting like ‘keys’
T snares are found on the target organelle what do they do?
They act like ‘locks’ which allows the binding of V snares causing an interaction between the vesicle and target organelle, using endocytosis.
Name some functions of the golgi apparatus
Further modification of proteins
Synthesis of glycolipids
Proteolytic conversion of pro-forms of proteins into mature forms (pro insulin)
Packaging of proteins destined for export into secretory vesicles or granules.
Targeting of proteins to lysosomes (addition of mannose-6-phosphate)
What is constitutive protein secretion?
Continuous secretion of a protein i.e. albumin from hepatocytes (or the protein is released as soon as it synthesized.)
What is regulated protein secretion?
secretion dependent on signalling before, for example insulin from beta cells in the pancreas. requires Calcium induction.
What is the signal recognition particle?
A single small molecule of RNA 6 different proteins Contains binding sites for; Signal sequence Ribosome An SRP receptor (docking protein) localised on the cytosolic face of the ER membrane
