PCTAIRE-1: characterization, subcellular distribution, and cell cycle-dependent kinase activity.
PCTAIRE-1 is a member of the cyclin-dependent kinase (cdk) family whose function is unknown. We examined the pattern of PCTAIRE-1 protein expression in a number of normal and transformed cell lines of various origins and found that the kinase is ubiquitous. Indirect immunofluorescence indicated that PCTAIRE-1 exhibits cytoplasmic distribution throughout the cell cycle. Confocal microscopy showed that PCTAIRE-1 does not colocalize with components of the cytoskeleton or with the endoplasmic reticulum. We found that endogenous PCTAIRE-1 and ectopically expressed PCTAIRE-1 display kinase activity when myelin basic protein is used as an acceptor substrate. Similar to other members of the cyclin-dependent kinase family, PCTAIRE-1 seems to require binding to a regulatory subunit to display kinase activity. PCTAIRE-1 activity is cell cycle dependent and displays a peak in the S and G2 phases. We show that the low level of kinase activity observed until the onset of S phase correlates with elevated tyrosine phosphorylation of the molecule.
Charrasse
S
S
Department of Oncology, Novartis Pharma AG, Basel, Switzerland.
Carena
I
I
Hagmann
J
J
Woods-Cook
K
K
Ferrari
S
S
D000199:Actins / Q000032:analysis; D018844:Cyclin-Dependent Kinases; D016213:Cyclins / Q000032:analysis; D005347:Fibroblasts / Q000737:chemistry / Q000201:enzymology; D015971:Gene Expression Regulation, Enzymologic; D006367:HeLa Cells; D006801:Humans; D017346:Protein Serine-Threonine Kinases / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D016196:S Phase / Q000502:physiology; D013347:Subcellular Fractions / Q000201:enzymology; D014404:Tubulin / Q000032:analysis
D000199:Actins; D016213:Cyclins; D014404:Tubulin; D017346:Protein Serine-Threonine Kinases; D018844:Cyclin-Dependent Kinases; C089463:PCTAIRE-1 protein kinase