The DNA-binding domains of Sox2 and Oct4. (A) The full-length Sox2 protein (315 amino acids [aa]) uses the HMG domain (79 aa, purple) to bind to DNA. The Oct4 protein (360 aa) has two DNA-binding domains, POUS (85 aa, orange) and POUHD (51 aa, red) connected by a linker of 15 aa. (B) The DNA-binding complex structure (Upper) and sequence motif (Lower) for the Sox2 HMG domain. The complex structure is based on PDB entry 1GT0. DNA sequence piece “CTTTGTT” is colored in cyan. (C) The complex structure (Upper) of Oct4 binding to its consensus sequence (Lower). The consensus sequences of the POUS and POUHD domains are colored in blue and green, respectively. The structure is based on PDB entry 3L1P.