Self-assembles into virion-like capsids that encapsulate RNAs and mediate intercellular RNA transfer. Arc2 protein is released from cells in extracellular vesicles that mediate the transfer of mRNA into neighboring cells. Homooligomer; homooligomerizes into virion-like capsids. Forms virion-like extracellular vesicles. The protein is evolutionarily related to retrotransposon Gag proteins. It contains structural elements found within viral Gag polyproteins originated from the Ty3/gypsy retrotransposon family and retains the ability to form virion-like capsid structures that can mediate mRNA transfer between cells. Tetrapod and fly Arc protein-coding genes originated independently from distinct lineages of Ty3/gypsy retrotransposons. Belongs to the ARC/ARG3.1 family.