Schistosoma mansoni: characterization and identification of calcium-binding proteins associated with the apical plasma membrane and envelope.

Calcium-binding proteins (CaBPs) of Schistosoma mansoni were purified by hydrophobic affinity chromatography. Metabolically labeled CaBPs were characterized using SDS-polyacrylamide gel electrophoresis followed by fluorography. A number of CaBPs were detected in total tissue extracts, apical plasma membrane, and soluble fractions of the apical bilayer complex, ranging from 15 to 205 kDa in their molecular masses. No CaBPs were discerned in the envelope of the apical bilayer complex. Two CaBPs were positively identified as calmodulin and gelsolin via immunoblot analyses. The possible role of CaBPs in surface signal transduction mechanisms has also been briefly discussed.