Nucleophosmin (NPM)

Author: Nat Pernick, M.D. (see Authors page)

Revised: 16 November 2015, last major update June 2005

Copyright: (c) 2002-2015,, Inc.

PubMed Search: Nucleophosmin [title]

Table of Contents
Definition / General
Definition / General
  • Also called B23, numatrin; gene at 5q35
  • Highly conserved non-ribosomal nucleolar phosphoprotein involved in assembling preribosomal particles into small and large ribosomal subunits
    • Binds with high affinity to ss nucleic acids, exhibits activity that destabilizes the RNA helix and is associated with the most mature nucleolar preribosomal ribonucleoproteins
  • May contribute active promoter to NPM-ALK
  • ALK promoter is normally silent in lymphoid cells

  • Hypothesis
    • IL-2 or T-cell mediated signals activate substrates; with NPM-ALK, get constitutive activation (note ALCL arises from activated T lymphocytes, which depend on IL-2 for growth and viability)
    • Fusion protein found in anaplastic large cell lymphoma (13-50%)
    • When present, can be used to differentiate from Hodgkin lymphoma