Probing the recognition of post-translational modifications by combining sortase-mediated ligation and phage-assisted selection.

Reversible post-translational modifications (PTMs) are key regulators of protein function and modulate a multitude of protein-protein interactions in signal transduction networks. Here, we describe a strategy for determining the modification preferences of PTM-binding proteins with only minimal protein amounts that can be obtained by immunoprecipitation from mammalian cell lysates. This method bases on the combination of sortase-mediated ligation and phage-assisted selection strategies.

Construction of an artificial cell membrane anchor using DARC as a fitting for artificial extracellular functionalities of eukaryotic cells.

The need to functionalize cell membranes in a directed way for specific applications as single cell arrays or to force close cell-to-cell contact for artificial intercellular interaction and/or induction concerning stem cell manipulation or in general to have a tool for membrane and cell surface-associated processes, we envisaged a neutral inactive membrane anchor for extracellular entities to facillitate the above mentioned functionalities. The silent Duffy antigen/receptor for chemokines (DARC) is a receptor-like membrane protein of erythrocytes and mediates no cell transduction not at least regarding a missing or truncated G-loop and therefore it seemed to be the candidate for our cell membrane anchor. We isolated the genetic information of DARC from human genomic DNA and cloned it in a mammalian cell line as a fusion protein via a suitable plasmid vector.