Endocrinology--Alpha & Beta Subunit Question

[ILikeSugar]

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First AID writes

alpha subunit--common subunit to TSH, LH, FSH, and hCG
beta subunit--determines hormone specificity

1.what is the significance of having a common alpha unit? Does that mean that a sky-high LH would end up stimulating the same receptors that TSH, FSH, and hCG do?

2. Do they mean that the beta subunit determines which receptors the hormone interacts with??


Any help would be appreciated!

 

[ArcGurren]

First AID writes
1.what is the significance of having a common alpha unit? Does that mean that a sky-high LH would end up stimulating the same receptors that TSH, FSH, and hCG do?

2. Do they mean that the beta subunit determines which receptors the hormone interacts with??


Any help would be appreciated!

1. No

2. No

The purpose is to show that there is partial homology in one subunit but the other subunit differentiates it by function and therefore by receptor specificity

 

[da8s0859q]

First AID writes
1.what is the significance of having a common alpha unit? Does that mean that a sky-high LH would end up stimulating the same receptors that TSH, FSH, and hCG do?

2. Do they mean that the beta subunit determines which receptors the hormone interacts with??


Any help would be appreciated!

1. No

2. No

The purpose is to show that there is partial homology in one subunit but the other subunit differentiates it by function and therefore by receptor specificity

I'm pretty sure I had something in UW which basically said that sky-high hCG can present with sx of hyperthyroidism, so there is some wiggle room on that first question.

 

[ArcGurren]

I'm pretty sure I had something in UW which basically said that sky-high hCG can present with sx of hyperthyroidism, so there is some wiggle room on that first question.

That's true - I forgot about that, my bad.

 

[Step1Hash]

I'm pretty sure I had something in UW which basically said that sky-high hCG can present with sx of hyperthyroidism, so there is some wiggle room on that first question.

We learned in my class that high hCG can bind the TSH receptor (hyperthyroidism) and can bind LH receptor (leading to gynecomastia). They explained as being because of the alpha subunit homology....so I would agree

 

[SlaveOfTCMC]

example:

The bHCG shares homology with TSH --> can lead to hyperthyroidism.

Just be aware that TSH levels actually DECREASE.

Yes it's a fairly obvious point, but just don't forget it.

 

[ILikeSugar]

Also, I just read up on a lady who was given a massive dose of hCG to stimulate ovulation since an hCG surge can mimic a FH surge.

so to conclude:
Since the alpha subunit is the same, they interact with the same types of receptors.

However, since the beta subunits are different, they end up being distributed at different places and for different durations (half-lives))

 

[ArcGurren]

...

 

[SlaveOfTCMC]

Actually, hCG simulates FSH by stimulating follicular maturation, not ovulation. The hormone usually used for stimulating actual ovulation is HMG, human menopausal gonadotropin (or Menotropin).

I'm going to have to contradict you on that one.

menotropin is a 4:1 mixture of FSH and LH. (to stimulate follicle)

hCG is used to simulate the LH surge.

Source: Kaplan, Goljan, OBGYN book.

 

[ArcGurren]

I'm going to have to contradict you on that one.

menotropin is a 4:1 mixture of FSH and LH. (to stimulate follicle)

hCG is used to simulate the LH surge.

Source: Kaplan, Goljan, OBGYN book.

Yeah, sorry. Goddamn I can't believe I mixed that up. I even have it written down in FA.