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. 2015 Nov 18;5:16214. doi: 10.1038/srep16214

Figure 1. Modeled structures of GRPR-targeted ProCAs and in silico docking of GRPR-targeted ProCAs to GRPR.

Figure 1

(a) Optimizing GRPR targeting peptide for molecular imaging by MRI. The modeled structure of ProCA1 variants (blue) with grafted GRPR targeting peptide from GRP or bombesin (red). ProCA1 is a protein-based MRI contrast agent derived from domain 1 of rat CD2 with several mutations to form a gadolinium (orange) binding pocket on its surface. ProCA1.B10 and ProCA1.G10 contain 10 amino acids at the C-terminal of bombesin and GRP, respectively. They share the same peptide sequence except one residue (H/Q) difference which is related to the GRP/bombesin-GRPR binding affinity. ProCA1.GRPR contains the whole sequence of bombesin with 14 amino acids. The ProCA1 and GRPR targeting peptide were connected through a flexible linker (yellow). These GRPR-targeted contrast agents are also PEGylated and conjugated with Cy5.5. (b) In silico docking of GRPR-targeted ProCAs to GRPR by HADDOCK.