Protein microarrays have matured to take on several conformations for greater flexibility and applicability. No longer mere offshoots of their DNA originator, protein microarrays have come into their own, taking on significant roles in labs. Researchers readily choose the arrays over other modalities to maximize efficiency.
Realizing how DNA microarrays were expediting genomics, researchers adopted the idea for faster progress in proteomics. So, they began spotting drops of proteins onto silicon wafers and glass slides. Antibodies and enzymes soon followed. Developers tested various slide coatings and immobilization techniques that best preserved the proteins’ conformations but minimized background noise. Proteins are attached directly to immobilizing molecules that are fastened to the slide. While some companies prefer attaching these molecules via covalent bonds, others opt for nonspecific adsorption with polymers or non-specific covalent bonding with activated surfaces of functional groups, such as aldehydes. These immobilizing molecules include antibodies against the specific molecules tagging the proteins, strepavidin for biotin-tagged proteins, glutathione for GST-fusion proteins, and nickel for histidine-tagged proteins.
With the technical details worked out, protein microarrays have increased the rate at which researchers can sort through the hundreds of thousands of proteins in the human proteome. For example, you can quickly find out which signaling proteins are present in a serum sample by pouring it onto an array spotted with hundreds of signaling proteins. This efficiency won over researchers who had once relied on more tedious techniques, such as two-dimensional gel electrophoresis, chromatography, and blots; these protocols not only require more manual labor, but also can only simultaneously screen a few proteins (at most).
Researchers have taken full advantage of the improvement. Within the few years of their existence, protein microarrays have unveiled a number of novel protein-protein interactions, such as the identification of certain substrates for protein kinases. Also, researchers can quickly isolate phosphorylated proteins to better understand signaling pathways. Antibody arrays have revealed the universe of cytokines in various samples, the types of proteins expressed in certain cell and tissue types, and biomarkers involved with disease development.
Many researchers now prefer beads and microplates as substrates for protein arrays. Companies have responded by offering a wide assortment of beads and plates printed with a multitude of antibodies and proteins. You can purchase the pre-printed arrays on their own, or packaged in kits that also include the necessary reagents. Kits come packaged with arrays that allow study of specific groups of cytokines, chemokines, growth factors, isotypes, kinases, and signaling molecules. If you don’t find exactly what you need, you can avail yourself of the many custom services. By purchasing multiplexing beads, such as the popular Luminex beads, you can exponentially increase screening efficiency.
You’ll find that fluorescence is the most popular mode of detection. Also well represented are chemiluminescent probes, quantum dots, and the traditional colorimetric methods of ELISAs. With up to one million proteins to discover, chances are that you’ll not only need all the colors and dyes of the spectrum, but also one of the items listed below.
The ProtoArray™ Protein Microarray is an advanced, high-content, functional protein microarray that allows scanning of thousands of proteins for biochemical interactions in one day. The human protein microarrays contain 5,000 full-length proteins representing multiple gene families arrayed in duplicate on nitrocellulose-coated or modified glass slides. ProtoArray™ technology enables multiple discovery efforts, including identifying protein biomarkers specific for cancers and autoimmune diseases, mapping protein-protein interactions, identifying kinase substrates for target discovery, and antibody specificity profiling for research and therapeutic development.
The Cell Signaling Antibody Array contains 224 different antibodies spotted in duplicate and represents multiple biological pathways including apoptosis, cell cycle, neurobiology, cytoskeleton, signal transduction and nuclear proteins. The antibodies are arrayed on a nitrocellulose coated slide and react with samples from human, mouse, and rat. The array is suitable for determining relative level of protein expression in cell or tissue extracts and can be used to establish protein expression profile comparisons of two samples.
Distributed exclusively by BioLegend, the Quansys Biosciences Q-Plex™ Array is a new platform for multiplex analysis of human, mouse, and rat cytokines. Highly sensitive, up to 16 different cytokines are quantified with only 30 ul sample in 2.5 hours total incubation. Q-Plex™ Arrays can currently yield up to 1344 data points in a 96 well plate – each point is a miniaturized sandwich ELISA. The chemiluminescent signal is captured with a CCD imaging system. New Stripwells™ Kits allow multiple assays to be run with a single plate.
