E4ORF6E1B55k

E4ORF6E1B55k is the designation used for a synthetic fusion protein construct that combines elements of the adenoviral proteins E4orf6 and E1B-55K. It is described in some virology research contexts as an engineered chimera intended to probe the interactions and functions of the E4orf6–E1B-55K complex, rather than as a naturally occurring standalone protein in standard adenoviral genomes.

Naming and origin

The name reflects the juxtaposition of the two parental open reading frames: E4orf6 and E1B-55K. The E1B-55K component typically denotes a ~55-kilodalton protein, while E4orf6 contributes regions implicated in protein interactions. In experimental designs, researchers may preserve specific domains from each partner to investigate their combined activities without introducing the full viral genome.

Biological rationale and research use

In adenovirus biology, E4orf6 and E1B-55K cooperate to form an E3 ubiquitin ligase complex that targets cellular proteins, including p53, for degradation. The fusion construct E4ORF6E1B55k is used to study how domains from the two proteins influence complex assembly, substrate recognition, and subcellular localization. Such constructs help map interaction interfaces, assess the contributions of individual regions to binding with Cullin-5 and other ligase components, and explore regulatory aspects of the degradation pathway in controlled model systems.

Structure and localization

Predicted localization for the fusion protein includes both nuclear and cytoplasmic compartments, with localization influenced by signals contributed by each parent protein. Structural features may include motifs from E4orf6 that mediate protein interactions and from E1B-55K that support oligomerization or substrate targeting, though exact architecture depends on the design of the construct.

Applications and limitations

E4ORF6E1B55k serves as a tool for dissecting the E4orf6–E1B-55K ubiquitin ligase axis and its substrates. As an engineered construct, its behavior may differ from native viral proteins, requiring validation in authentic viral contexts and appropriate biosafety considerations.

See also: E4orf6, E1B-55K, Cullin-5 E3 ligase, p53 degradation, Adenovirus.