Checkpoint Kinase 2 (CHEK2)

The longest human cDNA encoded a 543-amino acid protein with 83% identity to mouse Chk2 and 34% identity to Drosophila Dmnk, a protein highly expressed in ovaries for which a function in meiosis had been suggested. Human CHK2 protein is 26% identical to Rad53 and 26% identical to cds1+. Sequence analysis revealed a single forkhead-associated (FHA) domain, a 60-amino acid protein interaction domain essential for activation in response to DNA damage that is conserved in the Rad53/cds1+ family of kinases. CHK2 has a potential regulatory region rich in SQ and TQ amino acid pairs. Northern blot analysis revealed wide expression of small amounts of CHK2 mRNA with larger amounts in human testis, spleen, colon, and peripheral blood leukocytes. CHK2 complemented the lethality of a Rad53 deletion.