Glycobiology, 2000, Vol. 10, No. 8 773-779
© 2000 Oxford University Press
A sulfated polysaccharide from the sarcoplasmic reticulum of sea cucumber smooth muscle is an endogenous inhibitor of the Ca2+-ATPase
2Departamento de Bioquímica Médica, Instituto de Ciências Biomédicas and 3Laboratório de Tecido Conjuntivo, Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Caixa Postal 68041, Rio de Janeiro, RJ, 21941–590, Brazil
Vesicles derived from the endoplasmic reticulum of sea cucumber smooth muscle retain a membrane bound Ca2+-ATPase that is able to transport Ca2+ into the vesicles at the expense of ATP hydrolysis. In contrast with vesicles obtained from rabbit muscles, the activity of the Ca2+-dependent ATPase from sea cucumber is dependent on monovalent cations (K+>Na+>Li+). With the addition of highly sulfated polysaccharide to vesicle preparations from rabbit muscle, Ca2+ uptake decreases sharply and becomes highly sensitive to monovalent cations, as observed with vesicles from sea cucumber muscle. These results led us to investigate the possible occurrence of a highly sulfated polysaccharide on vesicles from the endoplasmic reticulum of sea cucumber smooth muscle, acting as an "endogenous" Ca2+-ATPase inhibitor. In fact, vesicles derived from the invertebrate, but not from rabbit muscle, contain a highly sulfated polysaccharide. This compound inhibits Ca2+ uptake in vesicles obtained from rabbit muscle and the inhibition is antagonized by monovalent cation. In addition, sea cucumber muscles contain high concentrations of another polysaccharide, which surrounds the muscle fibers, and was characterized as a fucosylated chondroitin sulfate. Possibly the occurrence of sulfated polysaccharides in the sea cucumber muscles is related with unique properties of the invertebrate body wall, which can rapidly and reversibly alter its mechanical properties, with change in length by more than 200%.
1 To whom correspondence should be addressed
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  D. C. F. da Costa and A. M. Landeira-Fernandez Thermogenic activity of the Ca2+-ATPase from blue marlin heater organ: regulation by KCl and temperature Am J Physiol Regulatory Integrative Comp Physiol, November 1, 2009; 297(5): R1460 - R1468. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A Landeira-Fernandez Ca(2+ )transport by the sarcoplasmic reticulum Ca(2+)-ATPase in sea cucumber (Ludwigothurea grisea) muscle J. Exp. Biol., January 3, 2001; 204(5): 909 - 921. [Abstract] [PDF]
|
|