Nucleophosmin (NPM1) also known as B23, is a novel substrate for G-protein-coupled receptor kinases (GRKs). NPM1 belongs to the nucleoplasmin family of proteins, made of the nucleophosmin, nucleoplasmin (NPM2), and NPM3 (1). GRKs phosphorylate, desensitize, and traffic GPCRs. In addition, they phosphorylate non-receptors substrates, thus potentially regulating a variety of cellular processes (2). GRK5 and GRK6 are found in nucleus and may be regulated by Gq signaling (3,4). GRK5 has been shown to phosphorylate NPM1. GRK5 phosphorylate NPM1 on Ser4, and Thr199 in vitro. Ser4 phosphorylation is also targeted by PLK1 (5). It is of interest that GRK5 phosphorylation of NPM1 may confer resistance to cell death mediated by PLK1 inhibition. Phosphorylation of NPM1 at Ser4 by PLK1 is involved in mitotic spindle formation (5). Whereas phosphorylation of NPM1 at Thr199 by cyclin-dependent kinase 1 is involved in regulating the centrosome (6), whereas the phosphorylation of both Ser4 and Thr199 controls centrosome duplication (7). NPM1 is involved in a variety of functions, including the regulation of centrosomal duplication, the cell cycle, mitosis, apoptosis, and RNA and DNA replication. It also serves as a chaperone for proteins such as histone. NPM1 is overexpressed in number of cancers and thus, is a potential target for cancer therapeutics (8).
Predicted to work with mouse, rat and other homologues.
Detection
Anti-Rabbit IgG
Clonality
Monoclonal
Immunogen
A synthetic phospho-peptide corresponding to residues surrounding Ser4 of human phospho-NPM
Formulation
1X PBS, 0.02% NaN3, 50% Glycerol, 0.1% BSA
Isotype
Rabbit IgGk
Preparation
Protein A+G
Recommended Usage
1µg/mL – 0.001µg/mL. It is recommended that the reagent be titrated for optimal performance for each application. See product image legends for additional information.
Storage
-20ºC
Pseudonyms
Nucleophosmin, Nucleolar phosphoprotein B23, numartin, nuclear protein NO38