Fraunhofer Institute for Cell Therapy and Immunology, Branch Bioanalytics and Bioprocesses IZI-BBThe complexity of the human proteome probably ranges from one hundred thousand to several million different protein molecules. In terms of data interpretation, the situation is further complicated by the fact that not for every protein of multicellular organisms the function is known and that there are different functions depending on structural variations or interacting partners. Furthermore, the dynamic range of protein expression is very large.
In antibody microarrays, antibodies are immobilized. After incubation with tissue lysate or serum, the binding of proteins to the antibodies is detected either directly by »staining« the serum proteins or with suitable detection antibodies. The principle structure corresponds to a sandwich assay as in ELISA. In addition to antibodies, other classes of »binders« such as aptamers or anticalins can also be used.
The aim of using antibody microarrays is to analyse variations in the actual protein frequency, the occurrence of isoforms and other structural variations. The basic technical processes such as suitable surfaces, blocking of the surface to prevent non-specific binding and protocols that allow reproducible and reliable analysis are established at the institute. Antibody selection is done in cooperation with company partners. In addition to the analyses using antibody microarrays, the transcripts can be determined by real-time PCR or physical parameters.