It has an important role in regulating the packaging of the viral genome into the capsid.

The packaging signal is found in the positive-sense single-stranded RNA genome.

[2] This RNA element is conserved in Embecovirus (previously known as lineage A Betacoronavirus[3]), which includes mouse hepatitis virus (MHV), bovine coronavirus (BCoV), and human coronaviruses like HCoV-HKU1 and HCoV-OC43.

Notably, this element is absent from the other viral lineages which have evolved separate packaging signals.

The packaging signal has a conserved RNA secondary structure featuring four AGC/GUAAU internal loop motifs.