Lectin binding characteristics of male and female salivary gland proteins of Anopheles gambiae: Identification and characterization of female specific glycoproteins

Abstract

Male and female salivary gland proteins of Anopheles gambiae were analyzed on blots of SDS gels by lectin binding in order to identify female specific glycoproteins. At least six major and several minor protein bands were identifiable in the total female gland proteins which were not visible in the male glands. The proximal lateral region of the female gland contained minor proteins which were similar in electrophoretic pattern to male salivary gland proteins. The distal lateral region and the median lobe each contained four different predominant protein bands. Western blot analysis with seven biotinylated lectins showed a distinct pattern of glycosylation between male and female salivary glands. Concanavalin agglutinin (Con A) and Dolichos biflorus agglutinin (DBA) bound to the highest number of male and female salivary gland glycoproteins while Ricinus communis agglutinin (RCA) and wheat germ agglutinin (WGA) showed the least binding, recognizing at least five female specific salivary gland glycoproteins. Soybean agglutinin (SBA) and peanut agglutinin (PNA) displayed a similarity in their binding pattern and distinguished the most female specific glycoproteins. Con A binding of the different morphological regions of the female salivary gland detected seven glycoproteins in the distal lateral region and four in the median lobe with trace amounts of glycoproteins in the proximal regions. In contrast, SBA detected glycoproteins mostly in the median lobe including eight female specific glycoproteins. Four out of the eight female specific glycoproteins were also found in the distal lateral region. Enzymatic deglycosylation followed by lectin binding showed that salivary gland glycoproteins are predominantly asparagine linked N-glycans with some possible O-linked glycans.