High Quality Content by WIKIPEDIA articles! Joan Argetsinger Steitz (born 26 January 1941) is a molecular biologist at Yale University, famed for her discoveries involving RNA, including ground-breaking insights such as that ribosomes interact with mRNA by complementary base pairing and that introns are spliced by snRNPs, small nuclear ribonucleoproteins which occur in eukaryotes (such as yeasts and humans).