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3-D Electron Crystallography Reveals the “Off” State of Smooth Muscle Myosin.

Published online by Cambridge University Press:  02 July 2020

T. Wendt ,
D. Taylor ,
K. Trybus  and
K. Taylor
T. Wendt
Affiliation:
Institute of Molecular Biophysics, Florida State University, Tallahassee, FL32306
D. Taylor
Affiliation:
Institute of Molecular Biophysics, Florida State University, Tallahassee, FL32306
K. Trybus
Affiliation:
Institute of Molecular Biophysics, Florida State University, Tallahassee, FL32306
K. Taylor
Affiliation:
Institute of Molecular Biophysics, Florida State University, Tallahassee, FL32306
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Extract

The activity of myosin II from vertebrate smooth and non-muscle cells is controlled by phosphorylation of the regulatory light chain (RLC). Smooth muscle heavy meromyosin (HMM) is a truncated double-headed myosin molecule that is soluble at physiological ionic strength. Subfragments of myosin containing two heads retain phosphorylation dependent regulation but single headed subfragments do not and are always “In”(Cremo et al., 1995; Trybus et al., 1997) thereby implicating head-head interactions as a fundamental feature of regulation. We have used a positively charged lipid monolayer to obtain 2-D crystalline arrays of both the unphosphorylated, inactive form (I-form) and thiophosphorylated, activated form (P-form) from chicken gizzard smooth muscle HMM obtained from a Baculovirus expression system.

A comparison of averaged 2-D projections of both forms in negative stain at 2.3 nm resolution reveals distinct structural differences (Wendt et al., 1999). The two crystals have p2 symmetry but vastly different unit cell dimensions.

Type
Philadelphia—The Other Motor City: Muscle and Non-Muscle Motility. A Dedication to Dr. Lee Peachey
Information
Microscopy and Microanalysis , Volume 6 , Issue S2: Proceedings: Microscopy & Microanalysis 2000, Microscopy Society of America 58th Annual Meeting, Microbeam Analysis Society 34th Annual Meeting, Microscopical Society of Canada/Societe de Microscopie de Canada 27th Annual Meeting, Philadelphia, Pennsylvania August 13-17, 2000 , August 2000 , pp. 86 - 87
Copyright
Copyright © Microscopy Society of America

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References

References:

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