Hormonal Activation by phosphorylation or dephosphorylation - USMLE Forums
USMLE Forums Logo
USMLE Forums         Your Reliable USMLE Online Community     Members     Posts
Home
USMLE Articles
USMLE News
USMLE Polls
USMLE Books
USMLE Apps
Go Back   USMLE Forums > USMLE Step 1 Forum

USMLE Step 1 Forum USMLE Step 1 Discussion Forum: Let's talk about anything related to USMLE Step 1 exam


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 05-05-2011
INCOGNITO's Avatar
USMLE Forums Guru
 
Steps History: Step 1 Only
Posts: 343
Threads: 127
Thanked 524 Times in 192 Posts
Reputation: 534
Question Hormonal Activation by phosphorylation or dephosphorylation

I am wondering about how a hormone is activated EITHER BY phosphorylation or dephosphorylation?

Some enzymes are activated by dephosphorylation and others by phosphorylation ..

What's that?
Reply With Quote Quick reply to this message



  #2  
Old 05-05-2011
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 1,175
Threads: 38
Thanked 852 Times in 478 Posts
Reputation: 862
Default

Same mechanism as in pharma where it is G coupled, that's how I believe the peptide hormones worked.
Reply With Quote Quick reply to this message
  #3  
Old 05-05-2011
INCOGNITO's Avatar
USMLE Forums Guru
 
Steps History: Step 1 Only
Posts: 343
Threads: 127
Thanked 524 Times in 192 Posts
Reputation: 534
Default

Quote:
Originally Posted by patelMD View Post
Same mechanism as in pharma where it is G coupled, that's how I believe the peptide hormones worked.
i didnt study pharma yet
but couldnt understand yet
Reply With Quote Quick reply to this message
 
  #4  
Old 05-05-2011
USMLE Forums Newbie
 
Steps History: Step 1 Only
Posts: 9
Threads: 2
Thanked 4 Times in 4 Posts
Reputation: 14
Default

There's no concept to understand here, just memorize the factoid and move on ... dude
Reply With Quote Quick reply to this message
  #5  
Old 05-05-2011
USMLE Forums Guru
 
Steps History: Not yet
Posts: 298
Threads: 45
Thanked 718 Times in 210 Posts
Reputation: 728
Default

For Biochemistry, use the following two rules:

1. Anything that is activated by insulin is activated by DEphosphorylation (Why? Because insulin acts via a Tyrosine Kinase Receptor, which eventually activates a phosphatase --> Cleaves phosphate groups)

Example: Insulin increases fat synthesis. What is the rate-limiting enzyme of fat synthesis? Acetyl-CoA Carboxylase. Therefore ACC is activated by DEphosphorylation!


2. Anything that is activated by glucagon is activated by phosphorylation (Why? Because glucagon is acts via Gs pathway and thus eventually activates Protein Kinase A --> Adds phosphate groups

Example: Glucagon stimulates Glycogenolysis. What is the rate limiting enzyme? Glycogen Phosphorylase. Therefore this enzyme is activated by phosphorylation!

Simple as that This was a point of huge confusion for me as well until I watched Kaplan Biochem/Pharm. Definitely listen to all the Lionel Raymon videos on Pharm and Biochem if you have time (unless you are less than 2 weeks away from the exam, it's worth it). He is a brilliant teacher!
Reply With Quote Quick reply to this message
The above post was thanked by:
causca (05-05-2011), INCOGNITO (06-21-2011), Taiwan_Guy (05-07-2011)
  #6  
Old 05-05-2011
USMLE Forums Guru
 
Steps History: Not yet
Posts: 298
Threads: 45
Thanked 718 Times in 210 Posts
Reputation: 728
Default

Quote:
Originally Posted by causca View Post
There's no concept to understand here, just memorize the factoid and move on ... dude
I would disagree. Even in Micro, Pharm, and Biochem there are principles that can help us to understand the material and prepare us for questions that we have never seen before. Some things have to be memorized but we can group similar things together to make our studying easier.

This forum is so great because we can share all those patterns and principles that we pick up from our studies!
Reply With Quote Quick reply to this message



Reply

Tags
Biochemistry-, Endocrine-, Physiology-

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the USMLE Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Medical School
Choose "---" if you don't want to tell. AMG for US & Canadian medical schools. IMG for all other medical schools.
USMLE Steps History
What steps finished! Example: 1+CK+CS+3 = Passed Step 1, Step 2 CK, Step 2 CS, and Step 3.

Choose "---" if you don't want to tell.

Favorite USMLE Books
What USMLE books you really think are useful. Leave blank if you don't want to tell.
Location
Where you live. Leave blank if you don't want to tell.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Toll-Like Receptor 4 Activation fin-84 USMLE Step 1 Forum 3 11-03-2010 10:54 PM
Hormonal Effects on Mammogenesis achistikbenny USMLE Step 1 Forum 10 04-25-2010 08:22 PM
Trypsinogen activation peptide MLE-Love USMLE Step 2 CK Buzzwords 0 02-25-2010 07:49 PM
Phosphate Hormonal Control rasheed USMLE Step 1 Bits & Pieces 0 02-13-2010 05:27 PM
Pituitary Failure Hormonal Replacement lee-usmle USMLE Step 1 Bits & Pieces 0 09-28-2009 03:14 PM

RSS Feed
Find Us on Facebook
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

USMLE® & other trade marks belong to their respective owners, read full disclaimer
USMLE Forums created under Creative Commons 3.0 License. (2009-2014)