Maternal Embryonic Leucine Zipper Kinase (MELK)

Nagase et al. (1996) cloned MELK through the random sequencing of cDNA clones derived from a myeloid leukemic cell line. The deduced 651-amino acid protein shares 62% identity with Xenopus protein kinase p69Eg3. Northern blot analysis detected expression in placenta, kidney, thymus, testis, ovary, and intestine. Heyer et al. (1997) cloned mouse Melk by differential display PCR analysis using cDNA from the egg and 2- and 8-cell-stage embryo cDNA libraries as template. The deduced 644-amino acid protein contains an N-terminal serine/threonine kinase domain that includes all 12 typical catalytic subdomains, and a leucine zipper motif. The mouse and human proteins share 95% sequence identity in the kinase domain. Northern blot analysis in mouse detected restricted expression to spermatogonia in testis and to oocytes in ovary.