The human progesterone receptor (hPR) in T47D breast cancer cells is phosphorylated on at least nine different serine residues. We have previously reported the identification of five sites; three are hormone inducible (Ser102, Ser294 and Ser345), and their phosphorylation correlates with the timing of the change in receptor mobility on gel electrophoresis in response to hormone treatment. The other two sites, Ser81 and Ser162, along with the remaining sites, are basally phosphorylated and exhibit a general increase in phosphorylation in response to hormone. With the exception of Ser81, all of these sites are in Ser-Pro motifs, suggesting that proline-directed kinases are responsible for their phosphorylation. We now report that cyclin A-cyclin-dependent kinase-2 complexes phosphorylate hPR-B in vitro with a high stoichiometry on three sites that are authentic basal sites in vivo. One of these is Ser162, which has been described previously. The other two sites are identified here as Ser190 and Ser400. The specificity and stoichiometry of the in vitro phosphorylation suggest that hPR phosphorylation may be regulated in a cell cycle-dependent manner in vivo.
|Titolo:||Phosphorylation of human progesterone receptor by cyclin-dependent kinase 2 on three sites that are authentic basal phosphorylation sites in vivo|
|Parole Chiave:||Humans ; Amino Acid Sequence ; Protein-Serine-Threonine Kinases ; Binding Sites ; Receptors, Progesterone ; Phosphorylation ; Tumor Cells, Cultured ; CDC2-CDC28 Kinases ; Cyclin-Dependent Kinases ; Molecular Sequence Data ; Peptides ; Cyclin-Dependent Kinase 2 ; Serine|
|Settore Scientifico Disciplinare:||Settore BIO/13 - Biologia Applicata|
|Data di pubblicazione:||giu-1997|
|Digital Object Identifier (DOI):||10.1210/me.11.6.823|
|Appare nelle tipologie:||01 - Articolo su periodico|