He is currently the Director of the Bay Area Institute of Science at Altos Labs and an emeritus professor at the Department of Biochemistry and Biophysics of the University of California, San Francisco (UCSF).

[4] He entered the Free University of Berlin in 1973 to study chemistry, but the rigid way of teaching science did not engage him.

[4][5] In the last year of his Vordiplom (equivalent to a BSc) in 1976, he went on exchange to Vanderbilt University and conducted research under Thomas M. Harris at the Department of Chemistry on the biosynthetic pathway of slaframine, a fungal alkaloid that is toxic to cows.

[1] In 1983, he moved to the Department of Biochemistry and Biophysics of the University of California, San Francisco (UCSF) as an assistant professor.

[7] Walter became a Howard Hughes Medical Institute investigator in 1997, and served as the president of the American Society for Cell Biology in 2016.

[21] The same year, Kazutoshi Mori, at the time a postdoctoral fellow at the University of Texas Southwestern Medical Center, independently made the same discovery.

Theoretically, upon phosphorylation, this target will enter the cell nucleus and increase the production of UPR-target proteins.

[25][26] Walter also discovered the phosphorylation target of IRE1, which turned out to be another IRE1 molecule, a process known as trans-autophosphorylation,[27] and also the enzyme stitching the spliced precursor HAC1 mRNA together.

The ISR is the cell's response to stresses such as viral infection, ultraviolet light and the accumulation of unfolded and misfolded proteins.