muscle query

[Dave Rintoul]

Greetings, 

I am in the process of revising the companion volume for the next
edition of a major cell biology text.  These companion volumes consist
of questions (and answers) to assist in learning the mass of material
in the text proper.  These questions start out easy (essentially
vocabulary buiding) and progress through conceptual stuff to the
hardest questions, those dealing with analysis of real experimental
data gleaned from the literature.  Chapters for which I am responsible
include:

Actin/Myosin and the Intermediate filaments

I have been soliciting feedback and input on these topics, using the
bionet groups essentially as reviewers, critics, or whatever.  I have
discussed this with Dave Kristofferson, and he agrees that this is a
good use for the net, and falls under the NSF goal of support for
education, even though this textbook is a commercial product.  Because
of the latter complication, we have agreed to discuss only the student
exercises themselves and not announce the name of the textbook or its
publisher.

In the process of writing the chapter on actin/myosin, I wondered
about the following (evolutionary) question. 

Why have vertebrates evolved such a complex system for regulating
smooth muscle contraction (involving myosin light chain kinase,
phosphatase, calmodulin, protein kinase C etc.) when the invertebrate
system uses calcium-dependent changes in the light chains themselves,
and seems to work OK?  What obvious (or subtle) advantages are
hypothesized to be gained from the additional complexity?  What
experimental proof is there for any of these hypotheses?  Any
help will be appreciated, and all will be acknowledged in the
preface of the text.  You can reply here or directly to me at

drintoul at ksu.ksu.edu

Thanks




-- 
Dave Rintoul                 Internet: drintoul at ksu.ksu.edu
Biology Division - KSU     Latitude 39.18, Longitude -96.34
Manhattan KS 66506-4901                Compuserve: 71634,32
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