Human CpG binding protein (hCGBP) contains three cysteine-rich domains, two of which exhibit homology to the plant homeodomain finger domain and the third cysteine-rich domain conforms to the CXXC motif identified in DNA methyltransferase, human trithorax, and methyl-CpG binding domain protein 1. A fragment of hCGBP that contains the CXXC domain binds to an oligonucleotide probe containing a single CpG site, and this complex is disrupted by distinct oligonucleotide competitors that also contain a CpG motif(s). CBGP plays an important part in embryonic viability and peri-implantation development. Native hCGBP is detected as an 88- kDa protein by Western analysis and is ubiquitously expressed. CGBP trans-activates promoters that contain CpG motifs but not promoters in which the CpG is ablated suggesting that hCGBP is a transcriptional activator that recognizes unmethylated CpG dinucleotides.Synonyms: CFP1, CGBP, CXXC-type zinc finger protein 1, CXXC1, PCCX1, PHD finger and CXXC domain-containing protein 1, PHF18