Fuusioproteins

Fuusioproteins are artificially engineered polypeptides that combine functional domains from two or more proteins into a single polypeptide chain. By fusing distinct domains, a fuisioprotein can inherit properties such as enzymatic activity, binding specificity, subcellular localization, or stability from its components. Fusion can be achieved by joining coding sequences in a gene (genetic fusion) or by linking protein domains post-translationally; most medically and experimentally used fuisioproteins are produced by recombinant DNA methods and expressed in suitable host cells.

In design, the orientation of the fused parts, the choice of linker, and the expression system influence folding and function. Linkers are often flexible peptides (for example, repeated glycine–serine motifs) that provide necessary separation to prevent steric interference. Researchers select host organisms and expression conditions to achieve correct folding, disulfide bonding, and post-translational modifications.

Common types and examples include GFP or other reporters fused to proteins for localization studies, Fc fusions to enzymes or cytokines to extend half-life and enable purification, and bispecific or multispecific fuisioproteins that bring two targets into proximity or recruit immune effectors. Therapeutic fuisioproteins such as etanercept (TNF receptor–Fc) illustrate clinical use, as do enzyme replacement or diagnostic fusion constructs.

Applications span basic research, biotechnology, and medicine. They include tracking protein dynamics, targeted therapy, immobilized biocatalysis, and diagnostic biosensors. Challenges include misfolding, reduced activity upon fusion, immunogenicity, incorrect localization, and manufacturing complexity. Ongoing advances in linker engineering, structural modeling, and expression technologies continue to expand the utility of fuisioproteins.