Joan Argetsinger Steitz (born January 26, 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).
Steitz was born in Minneapolis, Minnesota. She grew up in Minnesota in the 1950s and 60s at a time when there were virtually no female role models in molecular biology. She attended the then all-girls Northrop College for high school.
In 1963, Steitz received her B.S. in chemistry from Antioch College, Ohio, where she first became interested in molecular biology at Alex Rich's MIT laboratory as an Antioch "coop" intern.
After completing her B.S., Steitz applied to medical school rather than graduate school since she knew of female medical doctors but not female scientists. She was accepted to Harvard Medical School, but having been excited by a summer working as a bench scientist in the laboratory of Joseph Gall at the University of Minnesota, she declined the invitation to Harvard Medical School and instead applied to Harvard's new program in biochemistry and molecular biology. There, she was the first female graduate student to join the laboratory of James D. Watson, with whom she first worked on bacteriophageRNA.
Steitz did her postdoctoral fellowship at the Medical Research Council (MRC) Laboratory of Molecular Biology at Cambridge (UK), where she interacted with Francis Crick, Sydney Brenner, and Mark Bretscher. At the MRC, Steitz focused on the question of how bacteria know where to start the "reading frame" on mRNA. In the process, Steitz discovered the exact sequences on mRNA at which bacterial ribosomes bind to produce proteins. In 1969 she published a seminal Nature paper showing the nucleotide sequence of the binding start points.
In 1970, Steitz joined the faculty at Yale. In 1975, she published the research for which she is most famous, demonstrating that ribosomes use complementary base pairing to identify the start site on mRNA.
In 1980, Steitz published another critical paper, identifying the novel entity snRNPs and their role in splicing. A snRNP is a short length of RNA, around 150 nucleotides long, that are involved in splicing introns from newly transcribed RNA (pre-mRNA) -- spliceosomes. Steitz's paper "set the field ahead by light years and heralded the avalanche of small RNAs that have since been disocvered to play a role in multiple steps in RNA biosynthesis," noted Susan Berget.
Steitz later discovered another kind of snRNP particle, the snoRNP, demonstrating conclusively that introns are not "junk DNA" as they had often been described. Her work helps explain the phenomenon of "alternative RNA splicing." Part of the reason her discovery is so important is that it explains how humans are able to have only double the number of genes of a fly. "The reason we can get away with so few genes is that when you have these bits of nonsense, you can splice them out in different ways," she said. "Sometimes you can get rid of things and add things because of this splicing process so that each gene has slightly different protein products that can do slightly different things. So it multiplies up the information content in each of our genes."
Steitz's research may yield new insights into the diagnosis and treatment of autoimmune disorders such as lupus, which develop when patients make antibodies against their own DNA, snRNPs, or ribosomes.
Steitz has commented on the sexist treatment of women in science, noting that a woman scientist needs to be twice as good for half the pay. She has been a "tireless promoter of women in science," noted Christine Guthrie, who described Steitz as "one of the greatest scientists of our generation."
Steitz (then Joan Argetsinger) married Thomas Steitz, now also a professor of biophysics and biochemistry at Yale and the winner of the 2009 Nobel Prize in Chemistry, in 1966.
Steitz and her husband have one son, Jon, who played baseball with the Milwaukee Brewers for three years and then entered Yale Law School in 2004, from which he graduated in 2007. Prior to entering law school, Jon earned a Bachelor of Arts in Molecular Biophysics and Biochemistry in 2002. Jon is married to Katherine Van Loon, a gastrointestinal cancer specialist at UCSF. At the time of their meeting, Van Loon was a Master of Public Health candidate at Yale University. Prior to that, Van Loon earned a Bachelor of Science in Biology from Duke University in 2000.
J.A. Steitz, "Polypeptide Chain Initiation: Nucleotide Sequences of the Three Ribosomal Binding Sites in Bacteriophage R17 RNA," Nature Dec. 6, 1969, v. 224, no. 5223, pp. 957–964. doi:10.1038/224957a0
^J.A. Steitz, "Polypeptide Chain Initiation: Nucleotide Sequences of the Three Ribosomal Binding Sites in Bacteriophage R17 RNA," Nature Dec. 6, 1969, v. 224, no. 5223, pp. 957-964.
^Joan Argetsinger Steitz and Karen Jakes, "How Ribosomes Select Initiator Regions in mRNA: Base Pair Formation between the 3' Terminus of 16S rRNA and the mRNA during Initiation of Protein Synthesis in Escherichia coli," PNAS, Dec. 1, 1975, v. 72, n. 12, pp. 4734-4738.
^Lerner MR, Boyle JA, Mount SM, Wolin SL, Steitz JA, "Are snRNPs involved in splicing?", Nature Jan. 10, 1980, v. 283, no. 5743, pp. 220-224.
^Elaine Carey, "Female scientist 'a hero in her field': Yale's Joan Steitz, 65 honoured", Toronto Star April 3, 2006, p.A04; (Available in archive).
^("Unless you know what's going on inside the department, it all looks perfectly reasonable. If a woman is a star, there aren't that many problems. If she is as good as the rest of the men, it's really pretty awful. A woman is expected to be twice as good for half as much.") "The Reluctant Feminist," The New York Times, April 8, 2001.