Expression from λ gt11: How is an inserted DNA fragment typically expressed when cloned into the lambda gt11 vector?

Introduction / Context:
λ gt11 is a classic expression cloning vector used to produce fusion proteins for immunoscreening. The vector is designed so that inserted DNA is fused in-frame with the lacZ gene, producing a β-galactosidase fusion polypeptide. This enables plaque immunoscreening with antibodies against the fusion partner.

Given Data / Assumptions:

• λ gt11 contains the lac promoter and the 5’ portion of lacZ.
• Cloning in-frame into the multiple cloning site yields a LacZ–insert fusion.
• Fusion proteins can be detected with anti-β-galactosidase or insert-specific antibodies.

Concept / Approach:
The vector architecture forces expression as a β-galactosidase fusion if the insert is properly oriented and in-frame. This facilitates expression screening and identification of antigenic clones directly on plates.

Step-by-Step Solution:

Verification / Alternative check:
Protocols for λ gt11 immunoscreening emphasize detecting LacZ–fusion antigens in plaques using specific antisera.

Why Other Options Are Wrong:

Common Pitfalls:
Frame-shifted inserts that abolish fusion; cloning in the wrong orientation; using inappropriate host strains lacking necessary lac expression components.

Final Answer:
As a β-galactosidase fusion protein from the lacZ gene.