Nucleolin: A Multifaceted Nucleolar Phosphoprotein

Fri, 03/08/2013 - 07:00

Nucleolin is a ubiquitous, nonhistone nucleolar phosphoprotein of exponentially growing eukaryotic cells and is present in abundance at the dense fibrillar and granular regions of nucleolus. Intact nucleolin is the major species and represents 5% of nucleolar protein in actively dividing cells. In non-dividing cells, degraded forms of various molecular sizes are predominantly expressed due to autodegradation (1).  Nucleolin has been shown to be expressed on the cell surface where it serves as a binding protein for variety of ligands implicated in various cellular processes and the synthesis of nucleolin has been shown to be positively correlated with increased rates of cell division.

IF analysis of Nucleolin in MCF-7 breast cancer cells. IF analysis of Nucleolin in MCF-7 breast cancer cells.

It is not surprising, therefore, that nucleolin levels are highest in tumors or other rapidly dividing cells (2). Nucleolin has been shown to be present at low levels in non-dividing cells and is preferentially associated with chromatin. The amount of nucleolin has been also found to be relatively low in serum-deprived cells as compared to serum fed cells.  Experimental evidence supports an essential role for nucleolin in cell proliferation and the control of nucleolin expression is very complex, phosphorylation being only one of several regulatory elements in the nucleolin tool box. Extensive phosphorylation of nucleolin by a casein kinase (CKII) in interphase and by cdc2 kinase during mitosis suggests that phosphorylation may be a mechanism for regulating nucleolin function during the cell cycle (3). Further investigation into these correlations is required to identify the mechanisms by which nucleolin performs these disparate tasks and is an open area of research. Novus Biologicals is in the forefront of your Nucleolin research needs and offers a wide variety of tools in the form of recombinant proteins, cell lysates and antibodies.

  1. PMID: 7689479
  2. PMID: 7474921
  3. PMID: 9270871

Novus Biologicals offers Nucleolin reagents for your research needs including:

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