Growing evidence indicates that the processing of asparagine-linked oligosaccharides is coupled with the quality control of glycoproteins in cells. Namely, the intracellular lectins operating as molecular chaperones, cargo receptors, and ubiquitin ligases recognize partially trimmed intermediates of high-mannose-type glycans and thereby govern the intracellular processes of folding, transport, and degradation of carrier polypeptides. These intracellular lectins have unique mechanisms to check folding states of glycoproteins and to sense the subcellular environmental conditions. This review provides an overview on our current knowledge of the structural and molecular basis for glycoprotein-fate determination in cells through sugar recognition by the lectins.
Imaging is an essential approach to understanding the physiological systems of organism. Luminescence imaging based on luciferase technology reveals biological phenomena from molecule to body by light. In this manuscript, we describe the characteristics of luminescence probes and lead to the world of a luminescence imaging.
CEL-III is a Ca2+-dependent hemolytic lectin isolated from the sea cucumber Cucumaria echinata. X-ray crystallographic analysis revealed that CEL-III is composed of two ricin-like carbohydrate-binding domains (domain 1/2) and an oligomerization domain (domain 3). After binding to the specific carbohydrate chains on erythrocyte membrane, CEL-III undergoes conformational change, which leads to formation of membrane pores composed of its oligomers. Carbohydrate-recognition mechanism of CEL-III and its relationship with self-oligomerization mediated by domain 3 are discussed.