In memoriam: Professor G.N. Ramachandran (1922-2001).

Few scientists contribute an idea of such clarity and power that it appears in all the discipline's textbooks and bears the author's name. For the contribution to be relevant and universally employed almost forty years after it first appeared is even less common. Structural biology lost the author of such an idea with the death of G.N. Ramachandran, whose picture appears on the cover of this issue of Protein Science. His seminal contribution is described in remembrances of Professor Ramachandran's life and career by colleague and co-author of the 1963 paper, C. Ramakrishnan. A perspective by George D. Rose follows, which articulates the enduring impact of that work.