NSP4

NSP4 is a viral protein that is encoded by the Rotavirus genome. It is unique among known viral enterotoxins in that it is encoded by a virus that replicates in the cytoplasm of the host cell. NSP4 is a multifunctional protein that has a role in viral morphogenesis, pathogenesis, and viral replication.

Structure

NSP4 is a glycoprotein that is approximately 20 kDa in size. It is a type II transmembrane protein that is anchored in the endoplasmic reticulum (ER) of the host cell. The protein has a short N-terminus cytoplasmic domain, a transmembrane domain, and a large C-terminus that extends into the ER lumen.

Function

NSP4 acts as an enterotoxin by altering the calcium homeostasis of the host cell. This leads to a disruption of the tight junctions between cells, leading to diarrhea. NSP4 also has a role in viral morphogenesis by acting as a viroporin, creating a channel in the ER membrane that allows for the release of newly formed viral particles.

Pathogenesis

The pathogenic effects of NSP4 are primarily due to its enterotoxin function. The disruption of calcium homeostasis leads to a loss of water and electrolytes from the cells, resulting in diarrhea. This is a major symptom of Rotavirus infection and is the primary cause of death in severe cases.

Role in Viral Replication

NSP4 also has a role in the replication of the Rotavirus. It is involved in the assembly and release of new viral particles from the host cell. The protein acts as a viroporin, creating a channel in the ER membrane that allows for the release of the newly formed viral particles.

See Also

• Rotavirus
• Enterotoxin
• Viroporin

NSP4 Resources
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