proteinexpression

Protein expression is the process by which cells synthesize proteins using genetic information encoded in DNA. Some sources refer to the concatenated form Proteinexpression, but standard terminology is protein expression. It includes transcription of a gene into mRNA, translation into a polypeptide, and subsequent folding and maturation. In research and industry, expression often refers to producing a defined protein in a chosen system.

Natural expression is regulated by promoters and transcription factors; expression levels depend on sequence, mRNA stability, and cellular conditions. Recombinant protein expression uses engineered DNA constructs to boost production in a host organism or cell-free system.

Host systems include bacteria (notably Escherichia coli), yeast (Saccharomyces cerevisiae, Pichia pastoris), insect cells (baculovirus systems), and mammalian cells (CHO, HEK293). Prokaryotic systems are fast and inexpensive but may lack eukaryotic processing; mammalian systems provide human-like modifications but are costly and slower.

Expression is commonly controlled by inducible promoters and optimized by codon usage, regulatory elements, and culture conditions. Induction, temperature, and media influence yield and solubility. Fusion tags such as His-tags or GST aid purification and detection.

Purification usually involves chromatography followed by quality control assays, including SDS-PAGE, mass spectrometry, and activity tests. Common challenges include misfolding, aggregation, incorrect post-translational modifications, and endotoxin risk in bacterial systems.

Applications span basic research, structural biology, drug development, vaccines, and industrial enzyme production. Effective expression requires careful design, appropriate biosafety considerations, and rigorous verification of sequence, purity, and function.