A 110-kD nuclear shuttling protein, nucleolin, binds to the neurite-promoting IKVAV site of laminin-1.
The basement membrane protein laminin and the IKVAV-containing sequence from the laminin alpha 1 chain have been found to promote the differentiation of primary neurons and a variety of neural cell lines. We previously reported that a 110-kd IKVAV-binding protein (LBP110) isolated from brain appears to be a member of the beta-amyloid precursor protein (APP) family by immunologic and functional studies, which showed that LBP110/APP is also important in neurite outgrowth (Kibbey et al.: Proc Natl Acad Sci USA 90:10150-10153, 1993). In the preparation of this binding protein, a contaminating IKVAV-binding protein of identical molecular weight, nucleolin, was also identified. Here we have studied the relationship between these binding proteins. We find that nucleolin binds specifically to the IKVAV sequence independently of LBP110/ApP. We have also demonstrated significant levels of nucleolin in mature brain and in differentiating neural cells, suggesting that nucleolin functions not only in cell proliferation and in ribosome biogenesis as was previously reported, but also in the differentiation and maintenance of neural tissue. Our identification of cytoplasmic and cell-surface nucleolin, an IKVAV-binding protein, suggests that this protein may function in signalling by extra-cellular matrix.
Kibbey
M C
MC
Laboratory of Developmental Biology, National Institute for Dental Research, NIH, Bethesda, Maryland 20892-4370, USA.
Johnson
B
B
Petryshyn
R
R
Jucker
M
M
Kleinman
H K
HK
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D015153:Blotting, Western; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D000939:Epitopes; D007150:Immunohistochemistry; D007797:Laminin / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D008297:Male; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism*; D016501:Neurites / Q000502:physiology*; D009687:Nuclear Proteins / Q000302:isolation & purification / Q000378:metabolism*; D009697:Nucleolus Organizer Region / Q000378:metabolism*; D016716:PC12 Cells; D010750:Phosphoproteins / Q000302:isolation & purification / Q000378:metabolism*; D011485:Protein Binding; D016601:RNA-Binding Proteins; D051381:Rats; D011916:Rats, Inbred F344; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D000097796:Nucleolin
D002352:Carrier Proteins; D000939:Epitopes; D007797:Laminin; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; D016601:RNA-Binding Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D000097796:Nucleolin; C085259:Lamr2 protein, mouse