Recent Progress in the Methodologies to Identify Physiological Ligands of Siglecs.

Siglecs, a family of receptor-like lectins, recognize glycoproteins and/or glycolipids containing sialic acid in the extracellular space and transduce intracellular signaling. Recently, researchers uncovered significant contributions of Siglecs in cancer immunity, renewing interest in this family of proteins. Previous extensive studies have defined how Siglecs recognize glycan epitopes (glycotopes).

Affinity-Switchable Lateral Flow Assay.

Lateral flow assay (LFA) has been a valuable diagnostic tool in many important fields where rapid, simple, and on-site detection is required, for applications such as pregnancy tests and infectious disease prevention. Currently, two types of LFAs are available: lateral flow immunoassay (LFIA) and nucleic acid lateral flow assay (NALFA). Both are generally used for the testing of proteins and nucleic acids.

Improved Stabilities of Labeling Probes for the Selective Modification of Endogenous Proteins in Living Cells and In Vivo.

To date, various affinity-based protein labeling probes have been developed and applied in biological research to modify endogenous proteins in cell lysates and on the cell surface. However, the reactive groups on the labeling probes are also the cause of probe instability and nonselective labeling in a more complex environment, e. g.

Self-Immolative Difluorophenyl Ester Linker for Affinity-Based Fluorescence Turn-on Protein Detection.

Currently most fluorogenic probes are developed for the analysis of enzymes, where a bond breaking or rearrangement reaction is required to transform a nonfluorescent enzymatic substrate into a fluorescent product. However, this approach cannot be used for proteins that do not possess enzymatic activities. In this article, we show that fluorogenic probes with a self-immolative difluorophenyl ester linker can mimic the bond disassembly processes of fluorogenic enzyme substrates for the rapid analysis of nonenzymatic proteins.

Imaging and Quantification of Secreted Peroxynitrite at the Cell Surface by a Streptavidin-Biotin-Controlled Binding Probe.

The ability to detect and image secreted peroxynitrite (ONOO ) along the extracellular surface of a single cell is biologically significant, as ONOO generally exerts its function for host defense and signal transductions at the plasma membrane. However, as a result of the short lifetime and fast diffusion rate of small ONOO , precise determination of the ONOO level at the cell surface remains a challenging task. In this paper, the use of a membrane-anchored streptavidin-biotin-controlled binding probe (CBP), ONOO-CBP, to determine quantitatively the ONOO level at the cell surface and to investigate the effect of different stimulants on the production of ONOO along the plasma membrane of macrophages is reported.

Target-activated streptavidin-biotin controlled binding probe.

Target-activated chemical probes are important tools in basic biological research and medical diagnosis for monitoring enzyme activities and reactive small molecules. Based on the fluorescence turn-on mechanism, they can be divided into two classes: dye-based fluorescent probes and caged-luciferin. In this paper, we introduce a new type of chemical probe in which the fluorescence turn-on is based on controlled streptavidin-biotin binding.

Fluorogenic Protein Labeling Probes to Study the Morphological Interplay between PreLamin and Mature Lamin.

Although many protein labeling probes have been developed to elucidate the trafficking and turnover processes of cell surface proteins, real-time tracking of intracellular proteins remains a challenging task. Herein, we describe a new design to construct a cell-permeable, photostable, and far-red fluorescent turn-on probe to enable no-wash, organelle-specific, and long-term visualization of intracellular SNAP-tagged proteins in living cells. When the probe was used in dual-color pulse chase labeling experiments to differentiate between preLamin and mature Lamin, our results reveal that the shape of mature Lamin can be altered by the newly synthesized preLamin and that this alteration is progressive, cumulative, and due to a concentration-dependent dominant-negative effect of preLamin.