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| Institute: |
Lab or Branch |
| NIMH |
Laboratory of Neurotoxicology |
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| Title: |
| Analysis of CD4 and FN interaction with
GCDFP-15/gp17 by ProteinChip Technology |
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| Authors: |
| E. Caputo, A. Camarca, R. Moharram, P.
Tornatore, B. Thatcher, J. Guardiola and B.M. Martin |
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| Abstract: |
| Gross cystic disease fluid protein (GCDFP-15),
also known as prolactin-inducible protein (PIP) is a specific
breast tumor marker. GCDFP-15/PIP is also identified as
gp17 and/or seminal actin-binding protein (SABP) from
seminal vesicles; and as extra-parotid glycoprotein (EP-GP)
from salivary glands. It is an aspartyl-proteinase with
specific fibronectin (FN)-degrading ability, suggesting
its potential role in mammary tumor progression and fertilization.
Other functions have been attributed to it based on its
ability to interact with CD4, actin, and FN, although
these are still under investigation. We demonstrated that
GCDFP-15 and gp17 expressed in pathological and physiological
tissues, respectively, showed different structural properties.
This suggested that depending on its conformational state
it could differently bind to these molecules and change
its function(s).
We investigated the interaction of GCDFP-15 and gp17
with CD4 and FN, two of the well-known binding-partner
molecules. We used protein chip technology, a biochemical
approach based on two powerful techniques, chromatography
(on protein chip surfaces) and mass spectrometry (on
Surface-Enhanced Laser Desorption Ionization Time of
Flight mass spectrometer). We created specific CD4 and
FN surfaces, with CD4 and FN covalently attached. GCDFP-15
and gp17 were incubated on these surfaces and the species
able to bind to CD4 or FN were directly detected by
SELDI-TOF MS. We found that gp17 was mainly involved
in the binding to CD4 as compared with its pathological
counterpart and we identified the specific FN and CD4
binding-domains on GCDFP-15/gp17. This may provide a
rationale for the effective modulation of its function(s).
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