Oligo- és poliszacharidok, proteoglikánok

Abstract

Abstract: After clearing up the confusion in the previously used nomenclature, the paper discusses the family of small-leucin-rich glycoproteins. After mentioning the family and its role in the organisation of the ground substance and in the regulation of inflammation, one unique molecule of proteoglycans is presented. This molecule is the inter-α-trypsin inhibitor. It has turned out that this peculiar molecule originally contains glycosaminoglycan beside the neutral carbohydrates. After summarizing the numerous connections of the proteoglycan molecule, the “self-sacrificing” nature of the molecule is presented. It is noted that the functions of the ovaries are also controlled by this molecule. The unique structure and fundamental function of the CD44 is also analysed. The CD44 is a transmembrane proteoglycan receptor with diverse functions and actions. The organisation has intramolecular, transmembrane sections, a stalk and one globular part and contains glycosaminoglycan and oligosacharids, too. The construction contains sialic acid residues at end positions of the molecular chains, which hinder it from joining other sialic acid structures in terminal positions. Therefore, this molecule has to be separated to open up a way for the sequencing neutral molecule (e.g., hyaluronan) to be attached. CD44 is the most important, but not the only receptor of hyaluronan. It can form connections with a lot of constructions, e.g., blood cells, the human endothelial, adventitial and mesenchymal. Human extracellular matrix proteinases can change the receptor’s structures. Both the molecular and the supramolecular complexes boast unique features. The giant hyaluronan chains can connect to hyaluronan-binding proteoglycans – particularly hyaladherins to hyaluronectins – to create supramolecular connections and networks. The molecular mass of the fragments of hyaluronan is in the range of some kDs, while the whole molecule weighs up to several million Ds. The fragments are independent masses and can form attachments by themselves. The fragments have important inflammatory effects. Previously unidentified proteoglycan fragments have also been identified. Five of the ten identified fragments are secreted after synthetizing and stored in the granula of human cells. These strange characteristics are connected to the features of chromogranins/secretogranins. Nevertheless, this is another system of the organism, the functional, molecular structures of which are synthetized in neuroendocrine cells. Orv Hetil. 2018; 159(16): 620–627.