Smooth Muscle Contraction

Smooth Muscle Contraction - binding protein 3 The Ca/CAL...

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Smooth Muscle Contraction ‘Cheat Sheet’ Skeletal muscle – contraction initiated by calcium binding to troponin complex of actin. Smooth muscle – contraction initiated by calcium-regulated phosphorylation of myosin. Given: 1. Actin as in skeletal muscle, but with no troponin complex. 2. Myosin made up of heavy and light chains. 3. A myosin light-chain kinase. 4. A myosin light-chain phosphatase. Sequence: 1. Intracellular calcium is increased by one of a number of mechanisms and from either extra- or intra-cellular sources. 2. The Ca++ binds to calmodulin (CAL), a somewhat ubiquitous intracellular
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Unformatted text preview: binding protein. 3. The Ca++/CAL complex activates a myosin light-chain kinase which phosphorylates the myosin. 4. The phosphorylation of the myosin light chains then allows the myosin ATPase to function. 5. Myosin and actin bind and release energy. 6. A myosin light-chain phosphatase dephosphorylates myosin inhibiting contraction. The level of tension is determined by a balance between the Ca++ regulated phosphorylation of myosin by the kinase, and the deposphorylation by the phosphatase. The activity of the phosphatase can also be regulated....
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This note was uploaded on 11/01/2009 for the course BIO 3110 at Cornell.

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Smooth Muscle Contraction - binding protein 3 The Ca/CAL...

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