background:
Human papillomaviruses, particularly type 16 (designated HPV16), infect the genital tract and may lead to cervical cancer. Protection against HPV16 is thought to be provided by neutralizing antibodies directed to the major caspid protein L1 of HPV16. HPV16 L1 forms the pentameric assembly unit of the viral shell, and the binding of HPV16 L1 to the cell surface without the involvement of minor capsid protein L2 is believed to be the first step of HPV16 infection. The L1-binding domain located near the SLCterminus of L2 binds L1 prior to completion of capsid assembly and is required for efficient encapsidation of the viral genome. In addition, the SLCterminus of L1 is necessary for both DNA binding and DNA packaging. Expression of the late gene L1 is restricted to the upper layers of the infected epithelium. HPV16 L1 is able to package unrelated plasmid DNA in vitro and deliver the foreign DNA to eukaryotic cells with the subsequent expression of the encoded gene. L1 shows a diffuse nuclear distribution whereas L2 is localized to punctate nuclear regions identified as promonocytic leukemia protein oncogenic domains (PODs). Coexpression of L1 and L2 induces a relocalization of L1 into the PODs.
Function:
Minor protein of the capsid that localizes along the inner surface of the virion, within the central cavities beneath the L1 pentamers. Plays a role in capsid stabilization through interaction with the major capsid protein L1. Once the virion enters the host cell, escorts the genomic DNA into the nucleus, in particular by promoting virion endosomal escape. It is involved, through its interaction with host dynein, in the intracellular microtubule-dependent transport of viral capsid toward the nucleus. Mediates the viral genome import into the nucleus through binding to host importins. Once within the nucleus, L2 localizes viral genomes to PML bodies in order to activate early gene expression for establishment of infection. Later on, promotes late gene expression by interacting with the viral E2 protein and by inhibiting its transcriptional activation functions. During virion assembly, encapsidates the genome by direct interaction with the viral DNA.
Subunit:
Interacts with major capsid protein L1. Interacts with E2; this interaction inhibits E2 transcriptional activity but not the DNA replication function E2. Interacts with host GADD45GIP1. Interacts with host HSPA8; this interaction is required for L2 nuclear translocation. Interacts with host importins KPNB2 and KPNB3. Forms a complex with importin alpha2-beta1 heterodimers via interaction with the importin alpha2 adapter. Interacts with host DYNLT1; this interaction is essential for virus intracellular transport during entry.
Subcellular Location:
Virion. Host nucleus. Note=associated with ND10 nuclear bodies.
Post-translational modifications:
Highly phosphorylated (By similarity).
Similarity:
Belongs to the papillomaviridae L2 protein family.
Database links:
UniProtKB/Swiss-Prot: P03107.1
Important Note:
This product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications.
|
|
