Comparative analysis of glue proteins in the Drosophila nasuta subgroup.

The patterns of protein fractions from total salivary glands and from glue plugs were compared in seven members of the Drosophila nasuta subgroup by the use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The glue protein patterns are member specific concerning the numbers and the electrophoretic mobilities of major and minor glue protein fractions. However, the major fractions of all subgroup members could be grouped into five SDS-PAGE domains according to the homologies of their electrophoretic mobilities, prominence of Coomassie blue staining, and PAS reaction. In all subgroup members, major fractions are involved in posttranslational modifications into larger protein molecules of the final glue. Quantitative estimations of the glue proteins in D. n. nasuta and D. n. albomicans reveal that they constitute between 55 and 60% of the total salivary gland proteins, whereas in D. melanogaster and in D. hydei the fraction is only 32 and 35%, respectively.