MECHANISMS OF PROTEIN DEPHOSPHORYLATION IN SMOOTH MUSCLE

Project: Research project

Description

The overall aim will be to investigate the mechanism of protein
dephosphorylation involved in the regulation of smooth muscle contraction.
Details of how myosin light chain kinase phosphorylates myosin light chains
and brings about activation of smooth muscle contraction have been well
characterized. Also, cAMP-dependent protein kinase is known to both
phosphorylate and inactivate myosin light chain kinase, as well as to cause
relaxation of smooth muscle. Specific phosphatases which dephosphorylate
myosin light chains or myosin light chain kinase thus would be expected to
have opposite effects on tension generation - relaxation in the case of the
former, and activation in the case of the later. However, we have
previously shown that smooth muscle phosphatase IV actually
dephosphorylates myosin light chains and increases tension at submaximal
Ca2+. This research is designed to test the ability of different
phosphatases to dephosphorylate myosin light chains and myosin light chain
kinase in skinned smooth muscle cells and to analyse their effect on the
physiological variables, contraction and relaxation to determine which
phosphatase is most likely to be operating in vivo. Inhibitors to type 1
phosphatase will be used to determine which types of phosphatase are
involved in the dephosphorylation of myosin light chains or myosin light
chain kinase. These inhibitors are known to inhibit phosphatase activity
in vitro and will be used to inhibit type 1 phosphatase activity in skinned
smooth muscle cells. Their effect on protein phosphorylation and tension
will be characterized. A more cautious approach of using antibodies which
are known to inhibit phosphatase activity "in vitro" will be used to
further characterize the phosphatase regulation. Results from these
studies should give us a better understanding of the role phosphatases play
in the regulation of contraction and relaxation in smooth muscle and
important information regarding the type of phosphatases involved. This
information is crucial for a complete understanding of the mechanisms
involved in the regulation of smooth muscle contraction in vivo.
StatusFinished
Effective start/end date7/1/876/30/91

Funding

  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health

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Phosphoric Monoester Hydrolases
Smooth Muscle
Myosin-Light-Chain Kinase
Myosin Light Chains
Proteins
Muscle Contraction
Myosins
Light
Cyclic AMP-Dependent Protein Kinases
Muscle Cells
Smooth Muscle Myocytes
Phosphorylation
Antibodies
Research

ASJC

  • Medicine(all)