Steitz was born in Minneapolis, Minnesota. She grew up in Minnesota in the 1950s and 60s at a time when there were no female role models in molecular biology. She attended the then all-girls Northrop College for high school.
After completing her undergraduate degree, Steitz applied to medical school rather than graduate school since she knew of female medical doctors but not women 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 Nobel Laureate James Watson, with whom she first worked on bacteriophageRNA.
In 1970, Steitz joined the faculty at Yale. In 1975, she published a research finding for which she is widely known, demonstrating that ribosomes use complementary base pairing to identify the start site on mRNA.
In 1980, Steitz in collaboration with Michael Lerner published another critical paper, using immunoprecipitation with human antibodies from patients with autoimmunity to isolate and identify the novel entities snRNPs (pronounced "snurps") and detect their role in splicing. A snRNP is a specific short length of RNA, around 150 nucleotides long, associated with protein, that is involved in splicing introns out of newly transcribed RNA (pre-mRNA), a component of the spliceosomes. Steitz's paper "set the field ahead by light years and heralded the avalanche of small RNAs that have since been discovered to play a role in multiple steps in RNA biosynthesis," noted Susan Berget.
Steitz later discovered another kind of snRNP particle, the snoRNP, involved in an important minority of mRNA splicing reactions. Via analysis of the genetic locations of the genes for snoRNPs, she demonstrated conclusively that introns are not "junk DNA" as they had often been described. Her work helps explain the phenomenon of "alternative RNA splicing." Her discovery of the snRNPs and snoRNPs explains a mysterious finding: humans have only double the number of genes of a fruit 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 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 (born Joan Argetsinger) married Thomas Steitz, also Sterling Professor of Molecular Biophysics and Biochemistry at Yale and the 2009 Nobel Prize in Chemistry laureate, in 1966. They have one son, Jon.
Eli Lilly Award in Biological Chemistry (1976)
Passano Foundation Young Scientist Award (1975)
Her nomination for the Royal Society reads:
Joan Steitz is one of the pioneers of the field of RNA biology who is world-renowned for her many seminal contributions. She showed how ribosomal RNA is used to initiate translation at the start site of mRNA. She discovered spliceosomes, the particles that are the sites of splicing of pre-messenger RNA into the final mature mRNA and elucidated many of their roles. She discovered that introns, which were thought to be inert, code for sno RNAs that target the modification of other cellular RNAs during their maturation. More recently she has found new roles for microRNAs in gene regulation.
^ abLerner, M. R.; Boyle, J. A.; Mount, S. M.; Wolin, S. L.; Steitz, J. A. (1980). "Are snRNPs involved in splicing?". Nature. 283 (5743): 220–4. doi:10.1038/283220a0. PMID7350545.
^Vasudevan, S.; Tong, Y.; Steitz, J. A. (2007). "Switching from Repression to Activation: MicroRNAs Can Up-Regulate Translation". Science. 318 (5858): 1931–1934. doi:10.1126/science.1149460. PMID18048652.
^Steitz, J. A. (1969). "Polypeptide Chain Initiation: Nucleotide Sequences of the Three Ribosomal Binding Sites in Bacteriophage R17 RNA". Nature. 224 (5223): 957–64. doi:10.1038/224957a0. PMID5360547.
^Thomas R. Cech and Joan A Steitz (2014) “The Noncoding RNA Revolution—Trashing the Old Rules to Forge New Ones.” Cell157 (1): 77-94.
^Woan-Yuh Tam and Joan A. Steitz, I1997) “Pre-mRNA splicing: the discovery of a new spliceosome doubles the challenge. Trends in Biochemical Sciences22(4): 132-137.
^Elaine Carey, "Female scientist 'a hero in her field': Yale's Joan Steitz, 65 honoured", Toronto Star April 3, 2006, p.A04; ("Archived copy". Archived from the original on September 27, 2007. Retrieved 2006-11-27.CS1 maint: archived copy as title (link)).
^("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.