kapsidprotein

Capsid protein, or kapsidprotein, is a structural protein that forms the capsid, the protein shell that encloses a viral genome. Capsid proteins protect the genome and organize its packaging, while also guiding delivery of the genome into new host cells during infection.

Capsids are typically built from many copies of one or a few distinct capsid proteins. They can display icosahedral or helical symmetry, depending on virus family. In many viruses, assembly can occur without the genome (empty capsids) and is aided by scaffolding proteins or proteolytic maturation steps that refine the shell after assembly.

Capsid proteins participate in host cell interactions, including attachment to receptors, uptake, and uncoating. After internalization, triggers such as pH changes or enzymatic processing promote destabilization and release of the genome.

Genetic organization varies among viruses. Some express capsid proteins from a single open reading frame; others produce a polyprotein that is cleaved by viral proteases to yield mature capsid components. The major capsid protein is usually the most abundant, while minor capsid proteins contribute to stability, assembly, or receptor binding.

Research on kapsidprotein combines structural biology and virology. Techniques such as cryo-electron microscopy and X-ray crystallography map capsid architecture, informing vaccine design, antiviral strategies, and nanotechnology applications that exploit virus-like particles.