Peptides binding

Peptide binding to calmodulin induces a large interdomain movement... 

Figure 6.21 Schematic diagram of the conformational changes of calmodulin upon peptide binding, (a) In the free form the calmodulin molecule is dumhhell-shaped comprising two domains (red and green), each having two EF hands with bound calcium (yellow), (b) In the form with bound peptides (blue) the a helix linker has been broken, the two ends of the molecule are close together and they form a compact globular complex. The internal structure of each domain is essentially unchanged. The hound peptide binds as an a helix.

The peptide-binding site is a hydrophobic groove flanked by the RT loop between pi and p2 and the n-Src loop between p3 and P4 (see Figure 13.28a). The latter is so named because neuronal Src has an insertion of six residues in this loop. The groove is lined with conserved aromatic residues. 

Morton, C.J., et al. Solution structure and peptide binding of the SH3 domain from human Fyn. Structure 4 705-714, 1996. 

Figure 15.19 Schematic representation of the peptide-binding domain of a class I MHC protein. The al and a2 domains are viewed from the top of the molecule, showing the empty antigen-binding site as well as the surface that is contacted by a T-cell receptor. (Adapted from P.J. Bjdrkman et al.. Nature 329 506-512, 1987.)...

Class 1 and class II MHC molecules bind peptide antigens and present them at the cell surface for interaction with receptors on T cells. The extracellular portion of these molecules consists of a peptide-binding domain formed by two helical regions on top of an eight-stranded antiparallel p sheet, separated from the membrane by two lower domains with immunoglobulin folds. These domains are differently disposed between the two protein subunits in class I and class II molecules. 

The three-dimensional structure of HLA-B27 at 2.1 A resolution suggests a general mechanism for tight peptide binding to MHC. Cell 70 1035-1048, 1992. 

Murthy, V.L., 5tern, L.J. The class II MHC protein HLA-Drl in complex with an endogenous peptide implications for the structural basis of the specificity of peptide binding. Structure 5 1385-1396, 1997. 

Natriuretic peptides are a family of peptide hormones. All of them contain a 17-amino acid long ring that is closed by a disulfide bond between two cysteine residues. ANP (atrial natriuretic peptide) is mainly expressed in the atria of the heart, whereas BNP (B-type natriuretic peptide) is synthesized in the ventricular myocardium. CNP occurs mainly in the endothelium and is thought to have a paracrine function. ANF and BNF lower blood pressure by a direct effect on smooth muscle and on the salt retention in the kidney. Natriuretic peptides bind and activate particulate guanylyl cyclases. 

Flynn, G.C., Chappell, T.G., Rothman, J.E. (1989). Peptide binding and release by proteins implicated as catalysts of protein assembly. Science 245, 385-390. 

Vanbuskirk, A., Crump, B.L., Margoliash, E., Pierce, S.K. (1989). A peptide binding protein having a role in antigen presentation is a member ofthehsp70 heat shock family.). Exp. Med. 170,1799-1809. 

A number of approaches have been followed in attempts to create even more potent and durable inhibitory peptides including various rational approaches to increase peptide binding affinities, stability, and half-life (Dwyer et al. 2007), and the use of peptides such as 5-helix bearing multiple HR domains (Dimitrov et al. 2005). 

These T cells recognize peptide antigens bound to Class 1 MHC molecules on the surface of the target cell. During viral infections, viral peptides bind to selfMHCl molecules and are subsequently expressed on the cell surface. The MHCl molecules of transplanted tissues are themselves recognized by the Tc cells. 

CHARLTON A J, BAXTER N J, KHAN M L, MOIR A J, HASLAM E, DAVIES A P, WILLIAMSON M P (2002) Polyphenol/peptide binding and precipitation. J Agric Food Chem. 50 1593-601. 

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