Soluble salivary proteins secreted by Schizaphis graminum

Schizaphis graminum (Rondani) (Homoptera: Aphididae), when feeding on a sucrose solution, secreted primarily three proteins of 154, 69, and 66 kilodaltons (kDa). The sequence of the first nine amino acids at the N‐terminus of the 66 and 69 kDa proteins was identical suggesting that they differ only in processing at the C‐terminus. The N‐terminus of the 154 kDa protein was different, yet had some similarity to the N‐terminus of the 66 and 69 kDa proteins. There was an immunological cross‐reaction between the 154 kDa and the 66 and 69 kDa proteins indicating some amino acid sequence similarity. The probable relationships of these proteins are discussed.