6GE1:
reference: Unraveling the structural basis for the exceptional stability of RNA G-quadruplexes capped by a uridine tetrad at the 3' terminus., Andralojc W, Malgowska M, Sarzynska J, Pasternak K, Szpotkowski K, Kierzek R, Gdaniec Z, RNA. 2018 Oct 19. pii: rna.068163.118. doi: 10.1261/rna.068163.118. PMID: 30341177

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).