This domain was identified in WD40 repeat proteins and Ring finger domain proteins [1]. The function of this domain is unknown. GCN2 is the alpha-subunit of the only translation initiation factor (eIF2 alpha) kinase that appears in all eukaryotes. Its function requires an interaction with GCN1 via the domain at its N-terminus, which is termed the RWD domain [1] after three major RWD-containing proteins: RING finger-containing proteins, WD-repeat-containing proteins, and yeast DEAD (DEXD)-like helicases. The structure forms an alpha + beta sandwich fold consisting of two layers: a four-stranded antiparallel beta-sheet, and three side-by-side alpha-helices [2].

1: Systematic identification of novel protein domain families associated with nuclear functions. Doerks T, Copley RR, Schultz J, Ponting CP, Bork P; Genome Res 2002;12:47-56. PMID:11779830

2: Solution structure of the RWD domain of the mouse GCN2 protein. Nameki N, Yoneyama M, Koshiba S, Tochio N, Inoue M, Seki E, Matsuda T, Tomo Y, Harada T, Saito K, Kobayashi N, Yabuki T, Aoki M, Nunokawa E, Matsuda N, Sakagami N, Terada T, Shirouzu M, Yoshida M, Hirota H, Osanai T, Tanaka A, Arakawa T, Carninci P, Kawai Protein Sci 2004;13:2089-2100. PMID:15273307