Human Prk is a conserved protein serine/threonine kinase involved in regulating M phase functions.
Human prk encodes a novel protein serine/threonine kinase capable of strongly phosphorylating casein but not histone H1 in vitro. prk expression is tightly regulated at various levels during different stages of the cell cycle in lung fibroblasts. The Prk kinase activity is relatively low during mitosis, G1, and G1/S, and peaks during late S and G2 stages of the cell cycle. Recombinant human Prk expressed through the baculoviral vector system is capable of phosphorylating Cdc25C, a positive regulator for the G2/M transition. Human prk shares significant sequence homology with Saccharomyces cerevisiae CDC5 and Drosophila melanogaster polo, both of which are essential for mitosis and meiosis. Full-length prk transcripts greatly potentiate progesterone-induced meiotic maturation of Xenopus laevis oocytes. On the other hand, antisense prk transcripts significantly delay and reduce the rate of oocyte maturation. When expressed in a CDC5 mutant strain of S. cerevisiae, human Prk, but not a deletional mutant protein, fully rescues the temperature-sensitive phenotype of the budding yeast. Taken together, prk may represent a new protein kinase, playing an important role in regulating the onset and/or progression of mitosis in mammalian cells.
Ouyang
B
B
Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, USA.
Pan
H
H
Lu
L
L
Li
J
J
Stambrook
P
P
Li
B
B
Dai
W
W
D000595:Amino Acid Sequence; D000818:Animals; D002364:Caseins / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism; D002478:Cells, Cultured; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry; D015536:Down-Regulation; D004330:Drosophila; D005347:Fibroblasts / Q000201:enzymology; D006801:Humans; D008175:Lung Neoplasms / Q000201:enzymology; D051379:Mice; D008938:Mitosis; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011493:Protein Kinase C; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D014982:Xenopus laevis; D020687:cdc25 Phosphatases
D002364:Caseins; D018797:Cell Cycle Proteins; D018076:DNA, Complementary; D012333:RNA, Messenger; C061570:protein kinase N; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C; C517009:CDC25C protein, human; C517010:Cdc25c protein, mouse; D020687:cdc25 Phosphatases