10.12.2012 Views

netLibrary - eBook Summary Structure-based Drug Design by ...

netLibrary - eBook Summary Structure-based Drug Design by ...

netLibrary - eBook Summary Structure-based Drug Design by ...

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

Document<br />

Figure 6<br />

Proposed receptor activation pathway for IFN-γ. (From Reference 53. Copyright 1995.<br />

The American Association of Immunologists.)<br />

Page 449<br />

and we took advantage of this as a means of introducing the IFN-γ peptides into these cells. The IFN-γ Cterminal<br />

peptides induced a potent antiviral state in the murine macrophages and upregulated expression<br />

of MHC class II molecules, both in a dose-dependent fashion [43]. These effects were demonstrated to<br />

be sequence specific, as a scrambled version of the murine C-terminal peptide lacked activity.<br />

Furthermore, a truncated form of the murine C-terminal peptide, lacking the sequence of basic amino<br />

acids (RKRKR), was also without activity. The absence of activity of this truncated peptide was linked<br />

directly to a loss of its ability to bind to the receptor [43]. Therefore, interaction of IFN-γ, via its Cterminus,<br />

with its cytoplasmic binding site is important for function and requires the presence of a<br />

region of basic amino acids near the C-terminus of the molecule.<br />

C. Structural Biology of IFN-γ and the IFN-γ Receptor<br />

<strong>Structure</strong>-function studies of IFN-γ carried out using the synthetic peptide approach and site-specific<br />

antibodies indicated that both the N- and C-terminal regions of the protein were not only functionally<br />

important, but also accessible at the surface of the molecule. The x-ray crystal structure of human IFN-γ<br />

has been determined and reveals that in the IFN-γ homodimer both the N- and the<br />

http://legacy.netlibrary.com/nlreader/nlReader.dll?bookid=12640&filename=Page_449.html [4/9/2004 12:11:51 AM]

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!