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PNB 3265 - Lecture 5 Questions And Answers 2024/2025 Update
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PNB 3265 - Lecture 5 Questions And Answers 2024/2025 Update
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PNB 3265 - Lecture 5 Questions AndAnswers 2024/2025 Update
Learning Goals ANS✔✔ Learning goal 1: To understand the structure of protein hormones and how they
differ from peptide hormones.
Learning goal 2: To understand the structure of steroid hormones
What do we refer to hormones as and what are we trying to do when using hormones? ANS✔✔
Remember, hormones are informational packets; Packets of info.
It's like you sending a text or an email. You want to control the behavior of other cells and the way you
do that is by producing compounds that allow you to do that.
What's a characteristic of peptides he has mentioned before? ANS✔✔ → They're small, under 100 aa.
→ They have a signal peptide because they're secretory. Anything which is secretory has a signal peptide
that doesn't distinguish them. But it's a combination of traits.
→ They have the additional sequences added at the beginning which allow for storage and processing in
the golgi. These are not necessary for proteins.
Are proteins just a longer peptide? ANS✔✔ No, they are not just longer peptides
What are proteins usually coded with? ANS✔✔ SP, additional proteins
,Are there C or N terminal modifications in proteins? ANS✔✔ → No C- or N- terminal modifications
- This does not mean that they are not modified at all. See below for the classic modifications of these
proteins.
What kind of additions are made to proteins? ANS✔✔ → Addition of sugars (glycoproteins), acetylation,
lipid addition, Phosphorylation
Describe the homo and heterodimerization that occurs with other proteins. ANS✔✔ → Commonly
homo and heterodimerize with other proteins
- They are almost always dimers. The dimerization allows you to have two proteins to physically interact
with one another, changing the structure of one of the subunits. This is another control point.
Are proteins bigger? ANS✔✔ The other aspect about proteins is they're larger. They're just inherently
bigger. There is more mass and more potential areas that can communicate with other cells.
What is the biggest difference between proteins and peptides, besides the fact that they're bigger?
ANS✔✔ They are almost always dimers.
Many proteins are _________ heterodimers. ANS✔✔ Many protein hormones are glycosylated
heterodimers
What are the glycosylation aids? ANS✔✔ → Proper protein folding
→ Improved stability in blood
→ Essential for proper receptor binding
, What is the purpose of the C and N terminus in peptides? ANS✔✔ Remember what the C and N
terminus was all about. It is to stabilize the structure of peptides in blood because plasma is full of
proteases that want to do nothing but chop up peptides and convert them to amino acids. So remember
the term he used; the dwell time of peptides in blood is not very long. It is measured in minutes and
that's intentional.
We know proteins do no last for an infinite period of time. So what is done to make these things last
long enough? ANS✔✔ Well, proteins can also be processed in a different way. But they do not last for
an infinite period of time. Some proteins last a long time depending on what type they are (ex. Albumin
lasts a long time). But these proteins don't.
One way that you ensure that they last long enough is you don't do the N and C terminal modifications.
Rather, you do things like glycosylation. And that allows you to ensure that the protein has the right
structure because remember it has to have the right structure to fit into the pocket of the receptor. And
so it improves its stability in blood, allowing it enough time to exist so that it can find its target.
Within proteins there is a common ____ subunit and a variable ______ subunit. Which one is the
hormone here? ANS✔✔ Common α-subunit and variable β- subunits
→ β-subunit is the hormone
Heterodimers are only found in _________ ANS✔✔ Heterodimers are only found in vertebrates
What are some of the examples of the hormone heterodimers found in vertebrates? ANS✔✔ Luteinizing
hormone (LH), follicle stimulating hormone (FSH) and thyrotropin (TSH)
When the beta subunit binds to the alpha subunit, ANS✔✔ When the beta subunit binds to the alpha
subunit, it changes its structure. This is another example of a control point.
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