Fig. 1. Protein structure, sequence alignment and expression of Dnmt3L. (A) Schematic diagrams of mouse Dnmt3L (421 a.a.), Dnmt3a (908 a.a.), and Dnmt3b (859 a.a.) protein structures. The red block represents the PHD-like domain. The yellow bars represent the five highly conserved cytosine methyltransferase motifs in Dnmt3a and Dnmt3b. Dnmt3L contains motifs I, IV, VI, and part of IX, but not motif X. (B) Sequence alignment of the PHD-like domain. Conserved amino acid residues are highlighted in red while similar residues are highlighted in gray. The PHD-like domains are highly conserved among the Dnmt3 family members and the X-linked ATRX gene. (C) Sequence alignment of motifs I, IV, VI and IX. Note that Dnmt3L lacks the consensus amino acid residues PC in motif IV and ENV in motif VI, which form the catalytic center of cytosine methyltransferases. (D) A northern blot of total RNA (20 µg/lane) from undifferentiated ES cells (undiff) and differentiated embryoid bodies (diff) was hybridized with a Dnmt3L full-length cDNA probe. +, n, s and c represent wild-type and various Dnmt1 mutant alleles (Okano et al., 1998). The blot was rehybridized with a ß-actin probe as an RNA loading control. (E) Whole-mount in situ hybridization of E7.5 and E8.5 embryos using a Dnmt3L cDNA probe reveals high expression predominantly in the chorion. (F) X-gal staining of Dnmt3L^+/– adult mice carrying the IRES-ßgeo marker driven by the endogenous Dnmt3L promoter shows Dnmt3L expression in the oocyte and in male germ cells in the seminiferous tubule. Scale bar: 40 µm.