Recombinant Protein Production—Overcoming Low Expression Difficulties in obtaining large amounts of a protein encoded by a recombinant gene are often overcome by using which molecular tool?

Introduction / Context:
High-yield recombinant protein production typically requires specialized plasmids that drive strong transcription/translation and provide appropriate tags or secretion signals. These constructs are called expression vectors and are distinct from large-insert cloning vectors used for genome mapping.

Given Data / Assumptions:

• Goal: increase quantity of a specific recombinant protein.
• Host could be E. coli, yeast, insect, or mammalian cells.
• Need promoters, ribosome binding sites/KOZAK sequences, tags, and selection markers.

Concept / Approach:
Expression vectors place the gene under control of strong, regulatable promoters (e.g., T7, AOX1, CMV), optimize ribosome binding/translation initiation, and may include fusion tags for solubility and purification. This directly boosts protein yield compared with cloning-only vectors like BACs/YACs.

Step-by-Step Solution:

Verification / Alternative check:
Quantify yield via SDS-PAGE and activity assays; compare with non-expression vectors to observe dramatic increases in production.

Why Other Options Are Wrong:

• BACs/YACs are for cloning very large DNA fragments, not for high-level protein expression.
• “All equally” is incorrect; only expression vectors are designed for high-yield expression.
• CRISPR knock-outs remove genes; they do not promote overexpression.

Common Pitfalls:
Ignoring codon optimization, secretion signals, or chaperone co-expression; these further enhance yield with the right vector.

Final Answer:
Expression vectors