Cindy Dirscherl

• Planar surfaces with geometric protein patterns have been developed for various applications in biotechnology, such as orienting cells, arranging membrane proteins, or studying protein-ligand binding in massively parallel approaches. Geometric shapes and dimensions of protein patterns vary depending on the application. For the study of proteins in living cells, protein patterns in the micrometer range are commonly used; these are called protein micropatterns. Diverse lithography techniques have been used and were further developed to fabricate even complicated protein micropatterns on various surfaces. One of the first techniques to immobilize proteins in geometric patterns on glass surfaces was microcontact printing, which is a rather simple stamping approach that immobilizes proteins by physical absorption onto surfaces. MHC class I are peptide receptors that present the cell´s proteome at the cell surface to T cells. They thus play an essential role in the adaptive immune response against cells that are infected by viruses, bacteria, or that carry tumorigenic mutations. We have adapted the technology of protein micropatterns to the field of MHC class I and have used microcontact printing to immobilize anti-MHC class I antibodies on glass surfaces to develop an MHC class I capture assay. The development of this assay consisted of optimization and trial experiments; they finally established a robust assay that can be used to specifically capture MHC class I in living cells. In the field of MHC class I antigen presentation, we have identified two applications for the capture assay. First, a novel peptide binding assay was developed that allows for the monitoring of specific peptide binding to captured MHC class I in living cells. Further development of the assay led to the finding that the use of conformation-specific antibodies allows for differential capture of different structural forms of MHC class I. Excitingly, this enables the investigation of conformation-sp