SET domains are protein lysine methyltransferase enzymes. SET domains appear to be protein-protein interaction domains. It has been demonstrated that SET domains mediate interactions with a family of proteins that display similarity with dual-specificity phosphatases (dsPTPases) [2]. A subset of SET domains have been called PR domains. These domains are divergent in sequence from other SET domains, but also appear to mediate protein-protein interaction [3]. The SET domain consists of two regions known as SET-N and SET-C. SET-C forms an unusual and conserved knot-like structure of probably functional importance. Additionally to SET-N and SET-C, an insert region (SET-I) and flanking regions of high structural variability form part of the overall structure [5].

1: The Drosophila ash1 gene product, which is localized at specific sites on polytene chromosomes, contains a SET domain and a PHD finger. Tripoulas N, LaJeunesse D, Gildea J, Shearn A; Genetics 1996;143:913-928. PMID:8725238

2: Association of SET domain and myotubularin-related proteins modulates growth control. Cui X, De Vivo I, Slany R, Miyamoto A, Firestein R, Cleary ML; Nat Genet 1998;18:331-337. PMID:9537414

3: The PR domain of the Rb-binding zinc finger protein RIZ1 is a protein binding interface and is related to the SET domain functioning in chromatin-mediated gene expression. Huang S, Shao G, Liu L; J Biol Chem 1998;273:15933-15939. PMID:9632640

4: Structure of the SET domain histone lysine methyltransferase Clr4. Min J, Zhang X, Cheng X, Grewal SI, Xu RM; Nat Struct Biol 2002;0:0-0. PMID:12389037

5: Structure of SET domain proteins: a new twist on histone methylation. Marmorstein R; Trends Biochem Sci 2003;28:59-62. PMID:12575990