Substrats of G Protein Kinase

Stephen P. Driska PhD driska at
Mon Jan 29 18:37:22 EST 1996

95 (banaei at wrote:
: Could anybody give me some informations about the substrats of the
: G Protein Kinase in the Smooth Muscle Relaxation.

: Thanx forward

: my adresse : banaei at

: AB

	I'm not sure if you mean "G protein kinase" or "protein kinase G"
because if you mean G protein kinase, it seems that you have answered
your own question.

	On the other hand, if you want to know "How does cGMP cause 
smooth muscle to relax?", then  that is a different question.  The 
easy part of the answer is to say that it activates cGMP-dependent
protein kinase (sometimes called protein kinase G).  What the key
substrates are for this kinase in smooth muscle are is not absolutely
determined, to my knowledge.  Most people agree that this pathway
lowers the intracellular calcium concentration, and that protein
kinase G seems to phosphorylate the protein phospholamban, a protein
on the outside of the sarcoplasmic reticulum of smooth muscle.  This
results in increase calcium uptake by the sarcoplasmic reticulum.  An
author to search for in this area is Thomas Lincoln, who has done some
of these experiments.

	Another parallel mechanism is called "Calcium Sensitization",
but here, the amount of force produced by the contractile proteins 
can be different at the same calcium concentration.  A good review of
this appeared in the fall of 1994 (November) by Somlyo in the journal

		Good luck finding out what your looking for.

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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