A human amyloid precursor-like protein is highly homologous to a mouse sequence-specific DNA-binding protein

From a cDNA sequence, we have deduced the amino acid sequence for a human amyloid precursor-like protein (APPH) with > 92% identity to the CDEI binding protein (CDEBP) of the mouse and the fragmentary rat protein YWK-II of unknown function. Expression of APPH was found in all tissues examined. A striking homology of APPH to human amyloid precursor protein (APP) was observed. Overall identity accounts for 52.7%. However, there are three domains of APPH with remarkably higher similarities, corresponding to amino acid sequence positions 47-204 (76.6%), 308-567 (67.7%), and 694-763 (69.9%). Using an APPH antiserum, we localized APPH in nuclei of human interphase cells and found an increased synthesis of APPH in mitotic cells. Our results indicate that the highly conserved proteins human APPH, mouse CDEBP, and rat YWK-II are apparently homologues of a CDEI binding protein with indispensible function in mammalian genome segregation.