It has been hypothesized that an activator of Ca-ATPase co-exists with Ca-ATPase in the mouse lens. Though the Ca-ATPase activity could be measured from mouse lens homogenate, its activity could not be determined in individual soluble and insoluble fractions. The Ca-ATPase activity, however, could be detected when an activator of this enzyme such as calmodulin was added to the lens insoluble fraction. This enzyme in the lens insoluble fraction was activated also by addition of soluble fraction. The Ca-ATPase in homogenate was inhibited by chlorpromazine and N-(6-amino-hexyl)-5-chloro-l-naphthalenesulfonamide (W-7), which are calmodulin antagonists. When the mouse lens was incubated with W-7, the degree of the lens opacification increased in relation to W-7 concentration.
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