Peter Walter
Walter in 2021
Born	(1954-12-05)December 5, 1954 (age 71) West Berlin
Education	Free University of Berlin (Vordiplom) Vanderbilt University (MS) Rockefeller University (PhD)[1]
Known for	Signal recognition particle Unfolded protein response
Awards	Eli Lilly Award in Biological Chemistry Wiley Prize in Biomedical Science Gairdner Foundation International Award E.B. Wilson Medal Otto Warburg Medal Paul Ehrlich and Ludwig Darmstaedter Prize Ernst Jung Prize Mendel Lectures Shaw Prize in Life Science and Medicine Albert Lasker Award for Basic Medical Research Breakthrough Prize in Life Sciences
Scientific career
Fields	Molecular biology Biochemistry
Institutions	Rockefeller University University of California, San Francisco Howard Hughes Medical Institute
Thesis	Purification and characterization of an 11S protein complex required for the translocation of secretory proteins across the membrane of the endoplasmic reticulum (1981)
Doctoral advisor	Günter Blobel

Peter Walter (born December 5, 1954) is a German-Americanmolecular biologist andbiochemist. He is currently the Director of theBay Area Institute of Science atAltos Labs and anemeritus professor at the Department ofBiochemistry andBiophysics of theUniversity of California, San Francisco (UCSF).^[2][3] He was aHoward Hughes Medical Institute (HHMI) Investigator until 2022.

Walter was born and raised inWest Berlin in 1954. His parents owned apharmacy, and he was drawn tochemistry at a young age.^[4] He entered theFree University of Berlin in 1973 to study chemistry, but the rigid way of teaching science did not engage him. Instead, Walter became interested inbiochemistry, which studies the chemistry ofcells.^[4][5]

In the last year of hisVordiplom (equivalent to aBSc) in 1976, he went onexchange toVanderbilt University and conducted research under Thomas M. Harris at the Department of Chemistry on thebiosynthetic pathway ofslaframine, afungalalkaloid that is toxic tocows.^[6] Eventually, Walter completed hisM.S. at Vanderbilt in 1977.^[1]

At the encouragement ofStanford Moore, a biochemistry professor atRockefeller University and atrustee of Vanderbilt, Walter applied for thePhD programme at Rockefeller.^[6] He was placed on the waiting list, but after an accepted student went toHarvard University instead, was offered his place in 1977.^[4][5] He took his PhD underGünter Blobel, and obtained the degree in 1981.^[1]

After receiving his PhD, Walter stayed atRockefeller University as apostdoctoral fellow for a year, then became an assistant professor at the Laboratory ofCell Biology at Rockefeller.^[1]

In 1983, he moved to the Department ofBiochemistry andBiophysics of theUniversity of California, San Francisco (UCSF) as an assistant professor. Walter was promoted toassociate professor in 1986 and thenfull professor in five years later.^[1] He was chair of the Department of Biochemistry and Biophysics of UCSF between 2001 and 2008.^[7]

Walter became aHoward Hughes Medical Institute investigator in 1997, and served as the president of theAmerican Society for Cell Biology in 2016.^[8]

In 2021, there were reports that he would be joiningAltos Labs, a newbiotechnology company which reportedly focuses onanti-aging research.^[9][10] The next year, he retired from UCSF and the Howard Hughes Medical Institute in 2022,^[11][12] and joined Altos Labs as the Director of theBay Area Institute of Science when the company officially launched.^[13][14]

Walter currently sits on the Scientific Advisory Board of the Zentrum für Molekulare Biologie der Universität Heidelberg ofHeidelberg University.^[15]

Walter is a coauthor of the widely used textbookMolecular Biology of the Cell.^[16]

[1][2]

During his PhD atGünter Blobel's group, Walter purified aprotein complex required for moving proteins out of theendoplasmic reticulum (ER)^[17] and showed the complex selectively recognizes newly synthesizedsecretory proteins.^[18] He later confirmed the complex is in fact anucleoprotein and identified the RNA component essential for the complex's function. He also named the complexsignal recognition particle (SRP).^[19]

By the time Walter joined theUniversity of California, San Francisco (UCSF), researchers have established a connection betweenmisfoldedproteins in the ER and increased expression of a protein calledBiP, which is achaperone protein that helps other proteins fold correctly. This pathway is termed theunfolded protein response (UPR). However, howcells sense misfolded proteins and relays this information to thecell nucleus to increase the production of UPR-target proteins remains unclear.^[20]

In 1993, working onbaker's yeast, Walter found a gene,IRE1, which encodes akinase. The IRE1 protein is located across the ER membrane, so a part of it can detect unfolded proteins inside the ER and the other part canphosphorylate proteins outside of the ER.^[21] The same year,Kazutoshi Mori, at the time apostdoctoral fellow at theUniversity of Texas Southwestern Medical Center, independently made the same discovery.^[22]

Walter and Mori next independently sought thephosphorylation target of the IRE1 protein. Theoretically, upon phosphorylation, this target will enter the cell nucleus and increase the production of UPR-target proteins. Both of them arrived at the same gene,HAC1, in 1996.^[23][24] This discovery, however, was unexpected as the HAC1 protein is produced only after IRE1 detects unfolded proteins, meaning the protein is not present to be phosphorylated by IRE1.

This difference was mitigated by the finding of Mori and Walter that after IRE1 senses unfolded proteins, itsplices theHAC1 precursormRNA, which istranscribed from theHAC1gene, resulting in a mature mRNA that istranslated into the HAC1 protein.^[25][26] Walter also discovered the phosphorylation target of IRE1, which turned out to be another IRE1 molecule, a process known astrans-autophosphorylation,^[27] and also theenzyme stitching the spliced precursor HAC1 mRNA together.^[28]

In 2013, Walter's group identified a molecule that inhibits theintegrated stress response (ISR). The ISR is thecell's response to stresses such asviral infection,ultraviolet light and the accumulation ofunfolded andmisfoldedproteins. ISR activates theEIF2α protein, reducing mostprotein synthesis and increasing the production of some regulatorymolecules.^[29] His group found the inhibitor reversed EIF2α activation, and named itISRIB for "integrated stress response inhibitor". Remarkably, they foundmice injected with ISRIB had improved memory.^[30] ISRIB was licensed toAlphabet subsidiaryCalico in 2015.^[31]

• 1983 -Searle Scholar^[32]
• 1988 -Eli Lilly Award in Biological Chemistry^[33]
• 1989 -Sloan Research Fellowship^[34]
• 2002 - Member of theAmerican Academy of Arts and Sciences^[35]
• 2004 -Member of theNational Academy of Sciences^[36]
• 2004 -Associate Member of theEuropean Molecular Biology Organization^[37]
• 2005 -Wiley Prize in Biomedical Science^[38]
• 2006 - Member of theGerman National Academy of Sciences Leopoldina^[39]
• 2009 -Gairdner Foundation International Award^[40]
• 2009 -E.B. Wilson Medal^[41]
• 2011 -Otto Warburg Medal^[42]
• 2012 -Paul Ehrlich and Ludwig Darmstaedter Prize^[43]
• 2012 -Ernst Jung Prize^[44]
• 2013 -Mendel Lectures^[45]
• 2014 -Shaw Prize in Life Science and Medicine^[46]
• 2014 -Albert Lasker Award for Basic Medical Research^[47]
• 2015 -Vilcek Prize in Biomedical Science^[48]
• 2017 - Fellow of theNational Academy of Inventors^[49]
• 2018 - Member of theNational Academy of Medicine^[50]
• 2018 -Breakthrough Prize in Life Sciences^[51]
• 2023 -BBVA Foundation Frontiers of Knowledge Award^[52]

Walter is married to Patricia Caldera-Muñoz,^[53] whom he met inNew York City during his PhD years atRockefeller University and when Caldera-Muñoz was achemistry PhD student atNew York University.^[5] Before retiring, Caldera-Muñoz worked at theUniversity of California, San Francisco (UCSF) Science and Health Education Partnership, where she coordinated outreach to local science teachers.^[54][55]

Walter was diagnosed withneck cancer in 2009.^[56]

Scholia has a profile forPeter Walter(Q106367).

• 1954 births
• Living people
• American molecular biologists
• 21st-century American biologists
• German molecular biologists
• Howard Hughes Medical Investigators
• Members of the United States National Academy of Sciences
• University of California, San Francisco faculty
• Rockefeller University alumni
• Vanderbilt University alumni
• Free University of Berlin alumni
• Recipients of the Albert Lasker Award for Basic Medical Research
• Members of the National Academy of Medicine
• Members of the German National Academy of Sciences Leopoldina
• Fellows of the American Academy of Arts and Sciences
• Members of the European Molecular Biology Organization
• Searle Scholars Program recipients

• Articles with short description
• Short description is different from Wikidata
• Use mdy dates from November 2022
• Use American English from August 2023
• All Wikipedia articles written in American English
• Articles with hCards