The L2 proteins are about 450 to 550 residues long and are highly conserved. L2 is the minor capsid protein. Up to 72 molecules of L2 are incorporated into each virion particle and L2 could potentially fit into the center of all 72 L1 capsomeres. Upon infection, the virion binds initially to heparin sulfate proteoglycans and undergoes a conformational change that exposes the N-terminus of L2. Furin cleaves the N-terminus of L2 at a highly conserved motif (R-X-K/R-R) and this results in additional regions of L2 being exposed on the virion surface. These form epitopes that are good vaccine candidates as they generate cross-HPV type neutralizing antibodies. The virus subsequently binds to a secondary receptor and is internalized by endocytosis. L2 transports the viral genome to the nucleus; the L2-genome complex escapes the endosome and interaction of L2 with dynein further traffics it to nucleus. Within the nucleus, the L2 genome complex travels to ND10 nuclear bodies to establish an efficient infection. The L2 protein is expressed again late in infection when it assists in packaging progeny genomes into virions.
- LANL: The L1 and L2 Proteins
- Developing vaccines against minor capsid antigen L2 to prevent papillomavirus infection
- The role of furin in papillomavirus infection
- Viral entry mechanisms: human papillomavirus and a long journey from extracellular matrix to the nucleus
- Mechanisms of cell entry by human papillomaviruses: an overview
- 2013 Special Issue of Virology: L2, the minor capsid protein of papillomavirus