Capsid protein self-assembles to form an icosahedral capsid with a T=3 symmetry, about 32-35 nm in diameter, and consisting of 180 capsid proteins. Also acts as a suppressor of RNA-mediated gene silencing, also known as post-transcriptional gene silencing (PTGS), a mechanism of plant viral defense that limits the accumulation of viral RNAs (By similarity). Binds Ca(2+). Ca(2+) probably promotes virus assembly and stabilize the virus particle. Homodimer. Homomultimer. Belongs to the icosahedral plant coat protein family. Icosahedral capsid structure