Thank you for your support.
You know I never thought to look at Albert’s “Molecular Biology of
the Cell”. Silly me.
Dayton J. Ford, Ph.D.
Associate Professor of Biological Sciences
St. Louis College of Pharmacy
4588 Parkview Place
St. Louis, MO 63110
dford@xxxxxxxxxx
314-446-8463 voice
314-446-8460 FAX
From:
HAPS-L-owner@xxxxxxxxxxx [mailto:HAPS-L-owner@xxxxxxxxxxx] On Behalf Of Izak Paul
Sent: Wednesday, February 08, 2006
10:58 AM
To: HAPS-L@xxxxxxxxxxx
Subject: Re: [HAPS-L] "I'm
going to pick a fight" - Braveheart
Dayton,
you are right (and your textbook is wrong). In the IP3/DAG second messenger
system, Ca is not the 2nd messenger - it's IP3 and DAG which are
two second messengers in this pathway. Several different Cell & Molecular
Biology textbooks such as Alberts et al., Cooper & Hausman, etc. confirm
this. I guess that some of the Physiology textbooks need to be updated on this
topic.
Izak
-----------------------------------------------
Izak Paul, Ph.D.
Biological Sciences
Mount Royal College
4825 Mount Royal Gate SW
Calgary, Alberta
Canada
T3E 6K6
Office: (403) 440-6173
Fax: (403) 440-6664
email: ipaul@xxxxxxxxxx
|
|
"Ford, Dayton" <dford@xxxxxxxxxx>
Sent
by: HAPS-L-owner@xxxxxxxxxxx
02/08/2006 09:26 AM
Please
respond to HAPS-L
|
To: <haps-l@xxxxxxxxxxx>
cc:
Subject: [HAPS-L] "I'm
going to pick a fight" - Braveheart
|
Okay. Would someone please explain to me the rationale behind referring
to calcium as the second messenger in the IP3/DAG second messenger system,
rather than IP3 and DAG. In the cAMP system, cAMP is the molecule made that
then activates a cascade of events and is thus termed the second messenger. In
almost all of the texts that I have seen (including Guyton's 11th
ed.) the second messenger is said to be "Calcium". The only text that
seems to get it right is Berne, Levy, Koeppen, and Stanton's 5th ed. Wherin it is
stated that there are THREE systems. The cAMP system (with cAMP as the second
messenger), the Calcium-Calmodulin system (with Calcium as the second
messenger), and the Membrane Phospolipid system in which IP3 and DAG are the
second messengers. Other second messengers are listed (e.g. cGMP, NO, etc.),
but in an Intro to Physiology course we tend to focus only on the two main
pathways (cAMP, IP3/DAG). I have always argued that the second messengers in
the IP3/DAG system are IP3 and DAG. These are the molecules synthesized by the
enzyme activated by the G-protein. I thus tell my students to ignore what the
text says (Fox in my case) and refer to IP3 and DAG as the second messengers.
It becomes very confusing to my students when they see the cAMP path in their
textbook as:
Receptor
à G-Protein à Enzyme à Second
Messenger à Cellular Cascade
While
the IP3/DAG system is thus:
Receptor
à G-Protein à Enzyme à
Intermediate Molecule?? à Cellular Effect à Second
Messenger à Cellular Cascade.
Seems
to me that the only textbook that has attempted to clear up this confusion is
the Berne book. Anyone want to explain the
rationale behind this confusing bit of nomenclature??
Dayton J. Ford,
Ph.D.
Associate
Professor of Biological Sciences
St.
Louis College of Pharmacy
4588
Parkview Place
St.
Louis, MO 63110
dford@xxxxxxxxxx
314-446-8463
voice
314-446-8460
FAX
------------------------------------------------------------------------------------------------------------------------------
This communication is intended for the use of the recipient to which it is
addressed, and may
contain confidential, personal, and or privileged information. Please contact
the sender
immediately if you are not the intended recipient of this communication, and do
not copy,
distribute, or take action relying on it. Any communication received in error,
or subsequent
reply, should be deleted or destroyed