My professor has asked that the class find this out this semester, but
I have no clue! In a eukaryote cell membrane, there is a class of
protein known as G-protein. Of these G-proteins, there are several
kinds, one of which is called Gq (the q is subscripted). I need an
explaination of where the 'q' designation came from, and why 'q' in
particular is used.

---

Request for Question Clarification by andrewxmp-ga on 31 Oct 2005 12:11 PST

I can certainly tell you what Galpha(q) is and what it does, and how
it differns from subunit types e and i (the other two)  But really I
have no idea why it's designated "q" except for hypothesis based on
the protein's effectors.  Would this help or are you simply searching
for the basis for the subscript abbreviation "q"?  I know why "e" and
"i" are esued, but q does not really fit in that paradigm.

PS- Do not listen to those commenting on this question.  These types
of designations in science are very rarely arbitrary (subscripts are
THERE to specify something).  The other two, and presumably this one
as well, were not named solely on chronology of discovery, or some
other arbitrary point.  This is reason for having something such as
Google Answers, to hav substantiated backing for the answers given.

---

Clarification of Question by pendarvis1126-ga on 01 Nov 2005 07:52 PST

I'm looking specifically for information regarding the 'q' designation
and its origins. It doesn't SEEM arbitrary to me, but no one seems to
have much information on it at all.

Good luck with this one, your question got me intrigued, and I pulled
up some of the original articles that mention the Gq protein - I
couldn't for the life of me find a reference to its naming.

I hope someone finds an answer, although they probably won't for $2.50

-- Patrick

The q is probably/possibly arbitrary. The Gq class was the third class
discovered; no reason seems to be given for using q (The s and i
classes were previously known {stimulatory and inhibitory} and are
sensitive to pertussis toxin action while the q class is not.)

Search google scholar for the 1990 and 1991 PNAS papers by Strathmann
and Simon. There is also a 1991 Science article by them on the
subject, but you'll have to go to the library for that one.

Search strategy:   "g protein" gq
Search strategy:   author:strathmann "g protein diversity"

My guess is that brix24 is correct. The q designation is arbitrary. I
suggest that you email Melvin Simon at Caltech
(http://biology.caltech.edu/Members/Simon) for your answer.I think the
q designation originated in his lab.

To andrewxmp-ga;

You wrote "it differns from subunit types e and i (the other two)"

To clarify, there are more than two other subtypes of Galpha, (of
which e, to the best of my knowledge is not one), they include s, i,
t, z, q, o, olf.

I don't know if you are at all familiar with the naming of genes in
the drosophila literature, but I'll clue you in to something, gene
names such as frizzled, sonic hedgehog, frazzled, -- they don't have
meanings, they are there for the humor value of those that named them!
Naming in science can in fact be arbitrary, I don't claim that this
case happens to be...

You also wrote: "This is reason for having something such as Google
Answers, to hav substantiated backing for the answers given."

As dops-ga and brix24-ga aptly pointed out, the q designation first
appeared in a paper by Melvin Simon.

Three of us actually looked into this subject, did you?

If you would like a more thorough review of the subject, try a review
by Alfred Gilman, the 1994 winner of the Nobel Prize in Phys or
Medicine for his Gprotein work.  Or Pick up a biochemistry or cell
biology book.

Andrewxmp-ga has one very valid point, and that is, take everything
with a grain of salt - just becuase someone can say something - or
even if they can find a web source to back it up, doesn't mean it
holds true.

Thanks pforcelli! Oh that designations in Biology  were as meaningful
as andrewxmp-ga might imagine. I myself have published papers in top
journals with  numerical or alphabetic designations that have nothing
to do with the function of the protein, but instead with the order in
which they were discovered (or lab specific nomenclature).

I looked hard through the literature for any indication that the q
designation might have something to do with function (like inhibiting
q-class calcium channels), but at the time of the designation there
was no published role for this class of proteins.

If anyone comes up with the answer, please post it. I've been tempted
to email Melvin Simon myself.

pendarvis1126-ga -this question reminds me of a question on my
qualifying exams during Grad. school. The question referred to a
specific Western blot and asked why a band corresponding to protein X
with a highly similar epitope to protein Y didn't appear on the blot.
I don't remember the specifics anymore, but the answer was that it was
cropped out of the image prior to publication. I don't think anyone
that year got the answer right. The Prof. only knew the answer because
he had contacted the authors and asked.  The lesson, I suspect, that
we were supposed to learn from this was that what is shown is not
necessarily the entire story. Perhaps the point that your Prof. is
trying to make is that not all designations are functionally relevant.

My suggestion is that the "q" refers to "unique",.. in the sense that
G alpha q's were identified as the only G-proteins activating PLC.

Hi All,

I finally broke down and emailed Mel Simon regarding the Gq
designation. He very kindly indulged my curousity with the answer. The
q designation comes from  Micheal Strathmann, "he couldnt use the
front end of the alphabet because those early letters were reserved
for the classes of subunits, the Gz designation had been taken and Gx
seemed too obvious -- and so Gq."

Thanks for the question pendarvis.