The concept behind protein arrays is the immobilisation of sets of proteins, up to very large numbers, on solid supports, to perform miniaturised, multiplexed binding assays with a variety of potential ligands or interactants (see powerpoint presentation on right). HuProt v4 human proteome arrays as used at CPA comprise full length human proteins, many of which will retain their native conformation. HuProt arrays can be distinguished from arrays of peptides, used primarily to identify linear epitopes, or protein fragments, which may have some conformation but not necessarily that of the native protein.
HuProt arrays can measure hundreds or more binding interactions with antigens or analytes in parallel. The target range is most frequently represented by antibodies, where the arrays are used to validate binding specificity of polyclonals, monoclonals, single domains or recombinants, to identify the most avid primary target(s) and other less avid cross-reactants. Similarly they are used to identify the reactions of human serum/plasma autoantibodies prevalent in autoimmune disease conditions and in cancer patients.
The protein arrays can equally be used to assess the interactions of the immobilised proteins with other proteins (protein-protein interactions) and help to establish interaction networks. Nucleic acid binding can be used to identify transcription factor specificity or RNA-binding proteins. Interactions with small molecules, such as peptides or non-peptidic molecules (low mw drugs), can be used to identify off-target reactions of potential therapeutics.
The proteins on the array may themselves be interrogated as targets of enzyme modifications, such as glycosylation, phosphorylation or ubiquitination, all of which have been performed on the arrays.
While in principle the methods employed for these applications are very similar, as illustrated on the following pages, they must be tailored to the needs of the question being posed, e.g. through different concentrations and detection methods. Our team at Cambridge Protein Arrays will be pleased to assist you in deciding the best procedures to use for specific applications.