polysialyltransferase

Polysialyltransferase refers to a family of enzymes responsible for the synthesis of polysialic acid (polySia). PolySia is a linear homopolymer of N-acetylneuraminic acid (Neu5Ac) residues linked by alpha-2,8 glycosidic bonds. These enzymes are critical for the post-translational modification of the neural cell adhesion molecule (NCAM) and other glycoproteins. The extent of polysialylation on NCAM is dynamically regulated and plays a significant role in neural development, synaptic plasticity, and regeneration.

There are two main polysialyltransferases identified in mammals: ST8SIA2 (also known as PST or PSA-NCAM synthase) and ST8SIA4 (also known as PST2). These enzymes are glycosyltransferases that utilize CMP-Neu5Ac as the sugar donor. Their activity is influenced by various factors, including cellular localization and interactions with other proteins.

Polysialyltransferase activity is implicated in a range of biological processes. During embryonic development, high levels of polysialylation are observed, facilitating cell migration and neuronal network formation. In the adult nervous system, polysialia contributes to synaptic plasticity and learning. Dysregulation of polysialyltransferase activity has been linked to neurological disorders, including neurodevelopmental abnormalities and neurodegenerative diseases. Research continues to explore the therapeutic potential of modulating polysialyltransferase activity for treating these conditions.