Differential tyrosyl-phosphorylation of multiple mitogen-activated protein kinase isoforms in response to prolactin in Nb2 lymphoma cells.
Prolactin (PRL) stimulates mitogenesis and differentiative processes in a variety of cell types. Not all of the molecules involved in PRL signaling, which follows an initial PRL-receptor interaction, have been identified. In the present studies, PRL is shown to stimulate the differential tyrosyl phosphorylation of three isoforms (ERK-1, 2, and 4) of mitogen-activated protein kinases (MAP kinase) in a rat pre-T lymphoma cell line (Nb2). Evidence also suggests that PRL stimulates the tyrosyl phosphorylation of ERK-3, a MAP kinase isoform recently identified. When G1-arrested Nb2 cells are treated with 50 ng/ml oPRL, ERK-1 through 3 become tyrosyl phosphorylated within minutes (an indication of enzyme activation) and then become dephosphorylated within 30 min. Conversely, ERK-4 is rapidly tyrosyl phosphorylated by 5 min, and remains in this state for at least 1 hr.
Camarillo
I G
IG
Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
Linebaugh
B E
BE
Rillema
J A
JA
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases; D007527:Isoenzymes / Q000378:metabolism; D008223:Lymphoma / Q000196:embryology*; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048053:Mitogen-Activated Protein Kinase 6; D020928:Mitogen-Activated Protein Kinases; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism*; D011388:Prolactin / Q000494:pharmacology*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D051381:Rats; D011981:Receptors, Prolactin / Q000502:physiology; D015398:Signal Transduction; D013997:Time Factors; D014407:Tumor Cells, Cultured
D007527:Isoenzymes; D011981:Receptors, Prolactin; D019000:Phosphotyrosine; D011388:Prolactin; D011505:Protein-Tyrosine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; C102548:Mapk4 protein, rat; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048053:Mitogen-Activated Protein Kinase 6; D020928:Mitogen-Activated Protein Kinases