N-terminal chemokine receptor peptides

In Vitro Sulfation of N-Terminal Chemokine Receptor Peptides Using TPST... 

Here, we describe approaches for utilizing recombinant TPST-1 and TPST-2 to enzymatically sulfate N-terminal chemokine receptor peptides and for the characterization of these sulfopeptides. For a more expansive introduction to TPST enzymes and proteins containing sulfotyrosine post-translational modifications, see the following references Ludeman and Stone (2014), Moore (2003, 2009), Seibert and Sakmar (2008), and Stone, Chuang, Hou, Shoham, and Zhu (2009). 

Analysis of sulfotyrosine peptides and locahzation of sulfotyrosine positions in the presence of multiple potential sulfation sites can be a challenging task, in particular, if multiple sulfotyrosines are present in a single peptide chain, which is the case with most N-terminal chemokine receptor peptides. While mass spectrometry analysis of protein phosphorylation on a proteomics scale is well established, this is not the case for protein tyrosine sulfation. Due to the inherent lability of the sulfotyrosine sulfoester bond, partial or complete loss of the sulfotyrosine modification is generally observed as a neutral loss of SO3 (AMr = -80 Da) under standard mass spectrometry conditions. In particular, irrespective of the desorption/ionization method employed, positive... 

Loetscher P, Gong JH, Dewald B, Baggiohni M, Clark-Lewis I (1998) N-terminal peptides of stromal ceU-derived factor-1 with CXC chemokine receptor 4 agonist and antagonist activities. J Biol Chem 273 22279-22283... 

Residues affected by titration of N-terminal receptor-based peptides for various chemokines (shown as monomers). 

Fig. 4. Schematic illustration of chemokine-receptor interactions. The transmembrane helices of the receptor, shown as blue tubes, were derived from the structure of rhodopsin (PDB code 1L9H). The chemokine (pink) and the N-terminal extracellular domain of the receptor were derived from the IL8-CXCR1 peptide complex shown in Fig. 5 (PDB code lILP). Except for the N-terminus, the loops of the receptor are not displayed. The figure illustrates the relative size of the receptor and ligand, and the interaction of the receptor N-terminus along one face of the chemokine. The interaction orients the N-terminal signal domain towards the receptor as displayed here it is oriented towards the helical bundle, which may or may not be correct for some chemokines. (See Color Insert.)...

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