E4ORF1

E4ORF1 (E4 open reading frame 1) is a protein encoded by the E4 region of human adenoviruses. It is one of several early region 4 gene products expressed after infection and is used in research to study virus–host interactions and signaling pathways. E4orf1 is typically described as a cytoplasmic, membrane-associated protein that contains a C-terminal PDZ-binding motif, enabling interactions with PDZ domain-containing host proteins such as DLG1.

Through these interactions, E4orf1 can modulate cellular signaling pathways, including the PI3K-Akt pathway, leading to alterations in cell survival and metabolism. In experimental models, expression of E4orf1 can promote cell survival and influence endocytic trafficking and cell polarity, which may contribute to viral replication by delaying apoptosis and reprogramming the host cell environment.

Biological and research relevance: E4orf1 has been used as a tool to investigate Akt signaling and insulin/glucose uptake pathways, particularly in adipocytes, where its expression can activate Akt independently of insulin signaling. Its activity is context-dependent and varies by adenovirus type and cell type. E4orf1 is not a human gene and is specific to adenoviral genomes, studied primarily in virology and cellular signaling contexts.

See also: Adenovirus E4 region, PDZ-binding motif, PI3K-Akt signaling, DLG1.