Characterization and confocal imaging of calponin in gastrointestinal smooth muscle
M. P. Walsh, J. D. Carmichael and G. J. Kargacin Department of Medical Biochemistry, University of Calgary, Alberta, Canada. Calponin isolated from chicken gizzard smooth muscle binds in vitro to actin in a Ca(2+)-independent manner and thereby inhibits the actin-activated Mg(2+)-adenosinetriphospha...
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Veröffentlicht in: | American Journal of Physiology: Cell Physiology 1993-11, Vol.265 (5), p.C1371-C1378 |
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Sprache: | eng |
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Zusammenfassung: | M. P. Walsh, J. D. Carmichael and G. J. Kargacin
Department of Medical Biochemistry, University of Calgary, Alberta, Canada.
Calponin isolated from chicken gizzard smooth muscle binds in vitro to
actin in a Ca(2+)-independent manner and thereby inhibits the
actin-activated Mg(2+)-adenosinetriphosphatase of smooth muscle myosin.
This inhibition is relieved when calponin is phosphorylated by protein
kinase C or Ca2+/calmodulin-dependent protein kinase II, suggesting that
calponin is involved in thin filament-associated regulation of smooth
muscle contraction. To further examine this possibility, calponin was
isolated from toad stomach smooth muscle, characterized biochemically, and
localized in intact isolated cells. Toad stomach calponin had the same
basic biochemical properties as calponin from other sources. Confocal
immunofluorescence microscopy revealed that calponin in intact smooth
muscle cells was localized to long filamentous structures that were
colabeled by antibodies to actin or tropomyosin. Preservation of the basic
biochemical properties of calponin from species to species suggests that
these properties are relevant for its in vivo function. Its colocalization
with actin and tropomyosin indicates that calponin is associated with the
thin filament in intact smooth muscle cells. |
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ISSN: | 0363-6143 0002-9513 1522-1563 |
DOI: | 10.1152/ajpcell.1993.265.5.c1371 |