Smooth, slow and smart muscle motors.
Smooth muscle is a slow and economical muscle with a large variability in contractile properties. This review describes results regarding the relation between expression of myosin isoforms and the contraction of smooth muscle. The focus of the review is on studies of the organised contractile system in the smooth muscle tissue. The role of the myosin heavy chain variants formed by alternative splicing in the myosin heavy chain tail (SM1, SM2 isoforms) and head (SM-A SM-B isoforms) regions, as well as the role of essential light chains (LC17a, LC17b isoforms) for the variability of contractile properties are discussed. Smooth muscle also has the ability to alter its contractile properties in response to altered functional demands in vivo, e.g. during hypertrophic growth of urinary bladder, intestine, uterus and vessels and in response to altered hormone levels. These alterations involve changes in myosin expression and altered contractile kinetics. Non-muscle myosin has been shown to have a contractile function in some smooth muscle tissues and recent data on the kinetic properties of non-muscle myosin filaments in smooth muscle tissue are described.
Arner
Anders
A
Department of Physiological Sciences, Medical Faculty, Lund University, BMC F11, Tornavägen 10, SE-221 84 Lund, Sweden. Anders.Arner@mphy.lu.se
Löfgren
Mia
M
Morano
Ingo
I
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D005786:Gene Expression Regulation; D007700:Kinetics; D020409:Molecular Motor Proteins / Q000235:genetics / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology*; D018656:Muscle Fibers, Fast-Twitch / Q000502:physiology; D018657:Muscle Fibers, Slow-Twitch / Q000502:physiology; D009130:Muscle, Smooth / Q000502:physiology*; D018995:Myosin Heavy Chains / Q000235:genetics / Q000502:physiology; D018994:Myosin Light Chains / Q000235:genetics / Q000502:physiology; D024501:Nonmuscle Myosin Type IIB; D020033:Protein Isoforms / Q000235:genetics / Q000502:physiology; D024745:Smooth Muscle Myosins / Q000235:genetics / Q000502:physiology*
D020409:Molecular Motor Proteins; D018994:Myosin Light Chains; D020033:Protein Isoforms; D000255:Adenosine Triphosphate; D024501:Nonmuscle Myosin Type IIB; D024745:Smooth Muscle Myosins; C103815:nonmuscle myosin type IIB heavy chain; D018995:Myosin Heavy Chains