Ribosomal protein S6 cDNA from two Aedes mosquitoes encodes a carboxyl-terminal extension that resembles histone H1 proteins

Ribosomal protein S6 (rpS6) is the major phosphorylated protein on the eukaryotic ribosome. Because electrophoretic evidence suggested that the homolog of rpS6 from the mosquitoes Aedes albopictus and Aedes aegypti was measurably larger than Drosophila rpS6, we have now isolated full-length cDNAs encoding Aedes albopictus and Aedes aegypti rpS6. The mosquito rpS6 cDNAs encoded a 100 amino acid extension at the carboxyl-terminus, relative to rpS6 from humans and Drosophila. This region had homology to cDNAs encoding histone H1 from various species and accounted for the larger size of the mosquito protein on polyacrylamide gels. On Northern blots, the mosquito cDNA hybridized to a single band measuring approximately 1.2 kb.