Most abundant protein

Stephen P. Driska PhD driska at
Tue Jan 23 17:53:30 EST 1996

Scott A Hoffman (schoffma at wrote:
: Hello to the protein group.
: I have a couple of questions that maybe someone here can help me with.
: My question is:   what is the most abundant naturally occuring 
: protein?  I have heard that it is RUBISCO.  However, some people told me 
: that actin is the most abundant naturally occuring protein.  Does anyone 
: know which of these are correct (if any).  How is something like this 
: quantitated, in other words how does someone justify their answer to the 
: question of the most abundant protein.

: As a side question what is the largest naturally occuring protein?  How 
: big is it?  I have heard that it is a sarcomeric protein, but the name 
: eludes me.  
You may be referring to "titin".  It is mentioned now in Cell Biology
books (e.g. Alberts 3d ed.).  Kuan Wang is the person who did much of 
the important work, if you're about to start a Medline search.

	Can't help you on the other question; thought actin was the answer.
It seems like you could possibly have one protein most abundant by mass, 
and another one most abundant by number of copies, depending on the size...

: Thanks in advance.  Please feel free to post here or E-mail me directly.

: 	Scott Hoffman  <schoffma at>

Steve Driska, Physiology Department, Temple University Medical School
Philadelphia, PA 19140 USA (215) 707-3283 
driska at  
If I could think of something witty and clever to say, it would go right 
here ----->>    .........................

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