9458176 Ellington In vitro selection techniques will be used to determine how proteins containing arginine-rich motifs can specifically recognize their cognate RNAs. The possible sequence motifs available to both RNA and protein partners of the interface will be scanned and an attempt to identify `codes' for protein: nucleic acid interactions determined. %%% Commonalities in the complementary interfaces formed by proteins and nucleic acids are critical to understanding most life processes. In vitro genetic selections will be done in order to determine what set of protein sequence motifs. The range of possible `answers' to the molecular recognition `problems' will be investigated and improvements made, if possible. ***