ZipCode proteins

The following paper [ Proc. Natl. Acad. Sci. vol. 120 e2220026120n ’23 ] wasn’t as spectacular as it first appeared to me.  The authors found a peptide (sequence CGSPGWVRC  — or Cys Gly Ser Pro Gly Trp Val Arg Cys ) which binds to lung endothelial cells (and no other kind).  Moreover the receptor for CGSPGWVRC wasn’t another protein, but ceramide, a membrane lipid.

I was excited to think that something in our genome was making a peptide to bind to ceramide.  It didn’t make much sense because there is so much ceramide around.  It turns out that the peptide was found by phage display looking at zillions of peptides for those which bind specifically to lung endothelium.   It wasn’t an antibody and we don’t have a gene for it.

Such peptides have potential use, to target drugs to specific organs, and attaching a proapoptotic peptide to CGSPGWVRC   produced apoptosis of lung endothelium.  Such peptides clearly would be worth exploring for cancer chemotherapy, if they can be found for other organs.