Activation of receptor-associated tyrosine kinase JAK2 by prolactin. J Biol Chem 1994 Feb 18;269(7):5364-8
Date
02/18/1994Pubmed ID
7508935Scopus ID
2-s2.0-0027941433 (requires institutional sign-in at Scopus site) 318 CitationsAbstract
JAK family tyrosine kinases have recently been implicated in intracellular signal transduction by transmembrane cytokine receptors of the interferon (IFN) and hematopoietin receptor families. Using the prolactin (PRL)-dependent rat pre-T cell line Nb2, a PRL receptor-associated, candidate tyrosine kinase of 120-130 kDa was recently characterized (1). In the present work this protein is identified as JAK2, based upon reciprocal anti-JAK2 and anti-phosphotyrosine immunoprecipitation and immunoblotting. JAK2 underwent rapid and transient tyrosine phosphorylation in response to receptor activation, reaching peak levels within 5 min of exposure to 100 nM PRL at 37 degrees C. In vitro tyrosine kinase assays using either [gamma-32P]ATP and autoradiography or unlabeled ATP combined with anti-phosphotyrosine immunoblotting, demonstrated that the activity of JAK2 was stimulated by PRL. Phosphoamino acid analysis of JAK2 after in vitro tyrosine kinase assay revealed that the majority of phosphate was incorporated into tyrosine residues. Furthermore, JAK2 was associated with PRL receptors to a comparable extent before and after PRL binding, as demonstrated by anti-receptor immunoprecipitation and subsequent anti-JAK2 immunoblotting. We propose that binding of ligand to the PRL receptor activates preassociated JAK2, and that this enzyme generates the initial signal in the intracellular communication cascade.
Author List
Rui H, Kirken RA, Farrar WLMESH terms used to index this publication - Major topics in bold
Adenosine TriphosphateAnimals
Autoradiography
Cell Line
Enzyme Activation
Immunoblotting
Janus Kinase 2
Membrane Proteins
Phosphorus Radioisotopes
Phosphorylation
Phosphotyrosine
Prolactin
Protein-Tyrosine Kinases
Proto-Oncogene Proteins
Rats
Receptor Protein-Tyrosine Kinases
Receptors, Prolactin
Sheep
T-Lymphocytes
Tyrosine
