Upstream Binding Transcription Factor, RNA Polymerase I Like Protein 1 (UBTFL1)

UBTFL1 is a preimplantation-specific gene and is involved in early development, implantation, and embryonic stem (ES) cell derivation. The predicted 394-amino acid mouse protein shares 36% identity with Ubtf and encodes a SANT (SW13/ADA2/NCoR/TFIIIB) domain and 2 HMG-box domains, similar to Ubtf. Additional database analysis identified human UBTFL1, which shares approximately 54% amino acid identity with mouse Ubtfl1.The Hmgpi protein was first detected at the 4-cell stage and remained highly expressed in preimplantation mouse embryos. Hmgpi was expressed in both the inner cell mass (ICM) and the trophectoderm, and translocated from cytoplasm to nuclei at the blastocyst stage, indicating differential spatial requirements before and after the blastocyst stage.