Myosin II isoforms in smooth muscle: heterogeneity and function. Am J Physiol Cell Physiol 2007 Aug;293(2):C493-508
Date
05/04/2007Pubmed ID
17475667DOI
10.1152/ajpcell.00131.2007Scopus ID
2-s2.0-34547774119 (requires institutional sign-in at Scopus site) 81 CitationsAbstract
Both smooth muscle (SM) and nonmuscle class II myosin molecules are expressed in SM tissues comprising hollow organ systems. Individual SM cells may express one or more of multiple myosin II isoforms that differ in myosin heavy chain (MHC) and myosin light chain (MLC) subunits. Although much has been learned, the expression profiles, organization within contractile filaments, localization within cells, and precise roles in various contractile functions of these different myosin molecules are still not well understood. However, data supporting unique physiological roles for certain isoforms continues to build. Isoform differences located in the S1 head region of the MHC can alter actin binding and rates of ATP hydrolysis. Differences located in the MHC tail can alter the formation, stability, and size of the myosin thick filament. In these distinct ways, both head and tail isoform differences can alter force generation and muscle shortening velocities. The MLCs that are associated with the lever arm of the S1 head can affect the flexibility and range of motion of this domain and possibly the motion of the S2 and motor domains. Phosphorylation of MLC(20) has been associated with conformational changes in the S1 and/or S2 fragments regulating enzymatic activity of the entire myosin molecule. A challenge for the future will be delineation of the physiological significance of the heterogeneous expression of these isoforms in developmental, tissue-specific, and species-specific patterns and or the intra- and intercellular heterogeneity of myosin isoform expression in SM cells of a given organ.
Author List
Eddinger TJ, Meer DPAuthor
Thomas Eddinger PhD Bioological Sciences in the Biology department at Marquette UniversityMESH terms used to index this publication - Major topics in bold
ActinsAdenosine Triphosphate
Amino Acid Sequence
Animals
Humans
Hydrolysis
Molecular Sequence Data
Muscle Contraction
Muscle Development
Muscle, Smooth
Myocytes, Smooth Muscle
Myosin Heavy Chains
Myosin Light Chains
Myosin Type II
Nonmuscle Myosin Type IIA
Nonmuscle Myosin Type IIB
Phosphorylation
Protein Isoforms
Protein Structure, Tertiary
Smooth Muscle Myosins