Roles of viral oncoproteins

OncoproteinFunctionSource
E1- Highly conserved across HPV strains.
- Indispensable for initiating and regulating HPV replication.		[52]
E2- Multifaceted role in viral replication and transcription.
- Influences other critical processes.
- Can either activate or repress viral gene expression.		[53]
E4- Translated as an E1^E4 fusion protein.
- Leucine cluster motif is crucial for keratin binding.
- C-terminus facilitates self-association, forming structures reminiscent of amyloid fibers.
- Plays a pivotal role in regulating the cytokeratin network to aid viral release and dissemination.		[54]
E5- Significant in HPV-mediated carcinogenesis.
- Supports cellular hyperproliferation and cancer progression in both high-risk (HR-HPV) and low-risk (low-riskHPV) forms.
- Influences E6 and E7 activities.		[55, 56]
E6- Relatively large (18 kDa).
- Contains two zinc finger domains.
- Primarily found in the nucleus.
- Orchestrates the transformation of normal cells into malignant ones, significantly contributing to cervical carcinogenesis.		[57, 58]
E7- Approximately 100 amino acids long.
- Comprises three conserved regions (CR1, CR2, and CR3).
- A key player in cervical carcinogenesis through interactions with various host factors.		[59, 60]