A novel histone-stimulated protein kinase in normal and psoriatic epidermis.
During the course of studies on protein kinases in psoriatic epidermis, a novel histone-activated protein kinase activity was identified. This activity (referred to as PK-II because it was the second peak of protein kinase activity eluted from a DEAE column) was partially purified from the supernatant of an epidermal homogenate by DEAE-cellulose column chromatography. Although histone was not a substrate for phosphorylation, in the presence of histone, endogenous proteins of Mr 105 and 95 kDa were phosphorylated. Activity was not affected by Ca2+/phospholipid, cAMP, cGMP, cAMP-dependent kinase inhibitor, spermine, spermidine, calmodulin, EGF, or phorbol ester. Phosphorylation was specific for serine and threonine residues. A major peak of PK-II activity eluted from sepharose 6B with an apparent Mr of 100 kDa, suggesting that histone may stimulate autophosphorylation. The properties of PK-II resemble those recently described for a class of polypeptide-dependent protein kinases isolated from placenta, Ehrlich ascites tumor cells, and bakers' yeast. PK-II was significantly higher in psoriatic involved epidermis (32.6 +/- 11.6 pmol/min/mg protein) compared to psoriatic uninvolved epidermis (5.7 +/- 0.6 pmol/min/mg; p = 0.03) and normal epidermis (9.5 +/- 2.2 pmol/min/mg; p = 0.05). The function of histone stimulated protein kinase in epidermal function and its role in the pathophysiology of psoriasis remain to be explored.
Takematsu
H
H
Department of Dermatology, University of Michigan Medical School, Ann Arbor 48109-0528.
Fisher
G J
GJ
Voorhees
J J
JJ
D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D004817:Epidermis / Q000201:enzymology*; D006657:Histones / Q000502:physiology*; D006801:Humans; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D011565:Psoriasis / Q000201:enzymology*
D006657:Histones; D011494:Protein Kinases