Expression and Activity of Calpain A in Drosophila melanogaster.

Detecting calpain activity in Drosophila tissues is a fundamental tool to study calpain function. We use differential centrifugation to prepare membrane- versus cytosol-enriched fractions for measuring calpain activity with the fluorogenic substrate N-LY-AMC. With this method one can measure calpain A activity in wild-type flies and in several mutant fly backgrounds, revealing a strong correlation between in situ membrane distribution and in vitro determined activity measurements. Here we describe the steps for tissue preparation and calpain activity measurement in the Drosophila embryo.