Polyanion binding proteins data for five cellular polyanionic samples

The existence of interactions between many cellular proteins and various polyanionic surfaces within a cell is now well-established. The functional role of such interactions, however, remains to be clearly defined. The existence of protein arrays, with a large selection of different kinds of proteins, provides a way to better address a number of aspects of this question. We have therefore investigated the interaction between five cellular polyanions (actin, tubulin, heparin, heparan sulfate (HS), and DNA) and approximately 5,000 human proteins using protein microarrays in an attempt to better understand the functional nature of such interaction(s). We demonstrate that a large number of polyanion binding proteins exist which contain multiply positively-charged regions, are often disordered, are involved in phosphorylation processes, and appear to play a role in protein-protein interaction networks. Considering the crowded nature of cellular interiors, we propose that polyanion binding proteins (PABPs) interact with a wide variety of polyanionic surfaces in cells in a functionally significant manner. Keywords: Protein-Protein, protein-polyanion Interaction Experiments were conducted according to the manufacturer’s protocol. Briefly, protein arrays were probed with 120 ul of 50 ug/ml of each polyanion (actin, tubulin, heparin, heparan sulfate, and DNA) in the presence and absence of 0.15 M NaCl in the probing solution. After subsequent washings, the arrays were exposed to strepavidin-Alexa Fluor® 647. The arrays were then washed, dried, and scanned with the GenePix®4000B at 635 nm to acquire a fluorescence image. The resultant files were produced using GenePix® Pro 5.0 software. Each image was analyzed using the appropriate grid downloaded from the Invitrogen Inc. website. For all of the scanned images, a program available through Invitrogen Inc. (ProtoArray™ Prospector, v. 3.1.1) was used to obtain the identity of the proteins which demonstrated significant interaction with the probes.