Fig. 1

Several domain structures of C2H2-ZFPs. Three diverse forms of C2H2-ZFPs are described. Each C2H2-ZFP contains at least one KRAB structural domain, BTB domain, SCAN domain, SET domain and several zinc fingers which can bind to DNA sequences. In brief, the KRAB domain can be divided into two parts: the A-box (KRAB-A) and the B-box (KRAB-B). As shown in type 4, some C2H2-ZFPs contain a DUF3669 domain. Functionally, BTB domain is mainly responsible for transcriptional repression and protein degradation; SCAN domain is mainly responsible for protein binding and protein oligomerization; KRAB domain is mainly responsible for repression of transposable elements; SET domain is mainly responsible for protein methylation (mainly histones); C2H2 motif can bind to DNA, RNA, and proteins to perform different functions, but most of them bind to DNA.ZF: zinc finger; BTB: Broad-Complex, Tramtrack, and Bric-a-brac. KRAB:Krüppel-associated box; SCAN: SRE-ZBP, CTfin51, AW-1, and Number 18 cDNA; DUF3669:domain of unknown function 3669