Single-photon-level quantum memory for photonic states encoded in orbital angular momentum space

Abstract

attached to various proteins by taking advantage of the previously developed metabolic glycan labeling technique [2]. Simultaneously, they used a genetically encoded tag [4] to attach a FRET donor to the protein of interest. Since the tag is genetically encoded, the donor only resides on the specific protein of interest. Due to the distance constrain for FRET, only acceptor bound to the glycans on the same protein can be excited through intramolecular FRET, whereas the excess acceptors attached to other proteins will not respond. Therefore, the FRET effect serves to selectively image glycans of the same protein labeled with donor (Fig. 1). Using this technique, Chen and co-workers studied functional roles of sialylated glycans in β2 integrin activation. β2 integrins are adherent receptors expressed on the surface of leukocytes, and their activation is crucial in mediating leukocyte trafficking. They imaged the sialylated glycans on αXβ2 integrin and revealed that sialylation is important for activation; it would be almost impossible for such a study without the protein-specific imaging technique. The team also demonstrated generic applicability of their method to various cell-surface glycoproteins. Figure 1. The FRET-based methodology for protein-specific imaging of cell-surface glycans. Revised from [3] (Copyright 2014, American Chemical Society).