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The Magic of Sugar: Why Glycosylation is the Key Secret of Life
Most proteins synthesized in the rough endoplasmic reticulum undergo glycosylation.
Glycosylation is not limited to the endoplasmic reticulum, but also appears in the cytoplasm and nucleus in the form of O-GlcNAc modification. This means that glycosylation not only affects protein stability and function, but is also involved in cell-cell adhesion, supporting the effective interaction of immune system cells through the interaction of sugar-binding proteins (lectins). Below we will take a closer look at the mechanism of glycosylation and its importance in life.
Types of glycosylation
Glycosylation can be divided into several categories, depending on the type of sugar added and how it is linked:
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N-linked glycosylation is the most common form of glycosylation and involves attaching sugar chains to specific aspartic acid or arginine side chains. . This process is essential for the folding of many eukaryotic glycoproteins and their cell-to-cell attachment.
O-linked glycosylation occurs in the Golgi apparatus and involves attaching sugar chains to the hydroxyl groups of serine, threonine, and other amino acids. superior.
- GPI anchor glypiation refers to the process of linking sugar chains to lipids through GPI anchors, which allows proteins to effectively attach to cell membranes.
Glycosylation increases the diversity of the proteome because nearly every aspect of glycosylation can be altered, including the site of glycosidic linkage, sugar composition, and structure.
Physiological functions of glycosylation
Glycosylation affects human physiological functions in many aspects. First, many proteins have difficulty folding or stabilizing properly without glycosylation. The glycosylation process also serves as a quality control checkpoint in the endoplasmic reticulum to ensure that glycoproteins are correctly folded. In addition, glycosylation plays an important role in cellular immune responses and is involved in intercellular signal transduction and recognition. For example, in the ABO blood group system, the presence or absence of glycosylation directly determines the expression of blood group antigens, which in turn affects the immune system's response to different antigens.
Glycosylation and disease association
Recent studies have shown that abnormal glycosylation is closely related to a variety of diseases. Among them, glycosylation diseases can be divided into three categories: congenital glycosylation disorders, acquired glycosylation changes and non-enzymatic acquired changes. According to surveys, about 80% of congenital glycosylation disorders affect the nervous system, and there is still no effective treatment option. In the case of acquired changes, such as in rheumatoid arthritis, changes in glycosylation can prompt the body to produce antibodies against its own proteins, leading to abnormalities in the immune system.
Research has shown that mammalian glycosylation can significantly improve the efficacy of biotherapeutics in therapy and may become an important consideration in future drug development.
Future Research Directions
Future research will focus more on how glycosylation drives the evolution of life processes and its role in disease mechanisms. Scientists are exploring how to use this knowledge of glycosylation to improve disease diagnosis and treatment. For example, through advances in next-generation sequencing technology, scientists have made new breakthroughs in their understanding of glycosylation diseases and explored the genomic basis of these diseases.
Ongoing studies may also provide guidance on how to use glycosylation to promote health, perhaps helping to design a new generation of therapeutic drugs in the future. Will all this change our understanding of the nature of life?
