A. Filipek et al., CHARACTERIZATION OF CHICKEN GIZZARD CALCYCLIN AND EXAMINATION OF ITS INTERACTION WITH CALDESMON, Comparative biochemistry and physiology. B. Comparative biochemistry, 113(4), 1996, pp. 745-752
Using a procedure developed to purify calcyclin from mouse Ehrlich asc
ites tumor cells calcyclin was purified from smooth muscle of chicken
gizzard. Chicken gizzard calcyclin bound to phenyl-Sepharose in a calc
ium dependent manner as did mouse EAT cells and rabbit lung calcyclin
but appeared to be more acidic than its mammalian counterparts as reve
aled by ion exchange chromatography on Mono Q. Chicken gizzard calcycl
in bound Ca-45(2+) on nitrocellulose filters and exhibited a shift in
electrophoretic mobility on urea-PAGE depending on Ca2+ concentration.
Crosslinking experiments with BS3 showed that chicken gizzard calcycl
in was able to form noncovalent dimers. As indicated by a decrease in
maximum tryptophan fluorescence emission of caldesmon (about 14% at 1
: 1 molar ratio) and displacement of calmodulin from its complex with
caldesmon, chicken gizzard calcyclin binds caldesmon. This binding was
, however, much weaker than that of calmodulin and could not influence
the interaction of caldesmon with actin. In consequence, calcyclin wa
s unable to reverse the inhibitory effect of caldesmon on actin-activa
ted Mg2+-ATPase activity of myosin in the presence of Ca2+.