# How Scientists Taught Bacteria to Make Human Hormones > Genentech's 1979 patent on using engineered DNA to force bacteria to produce human proteins like insulin and growth hormones. - **Patent:** US 4356270 - **Original title:** Recombinant DNA cloning vehicle - **Owner:** Genentech Inc - **Granted:** 1982 - **Status:** Public domain (expired) - **Times cited:** 86 - **Field:** biotech, pharmaceutical ## What it does This patent describes a method for inserting synthetic DNA into a bacterial plasmid—a small, circular piece of DNA—so the bacteria acts like a factory. The key innovation is using 'codon optimization,' where the synthetic gene is written using the specific DNA 'language' that bacteria prefer, making them much more efficient at reading the instructions to build human proteins. By placing this gene between specific DNA 'cut sites' (restriction endonuclease sites), researchers could reliably insert and express mammalian hormones like somatostatin or insulin chains within a microbial host. ## What it does NOT cover - Does not cover naturally occurring DNA sequences that have not been synthetically modified for microbial expression. - Does not cover the use of non-bacterial hosts like yeast or mammalian cell cultures for protein production. - Does not cover the specific medical treatments or clinical applications of the hormones produced. - Does not cover gene editing techniques like CRISPR that modify DNA in place rather than using cloning vehicles. ## The clever bit The inventors realized that bacteria have a 'preference' for certain DNA codes; by rewriting the synthetic gene to use these preferred codons, they drastically increased the amount of human protein the bacteria could produce. ## Real-world examples 1. Synthetic human insulin (Humulin) 2. Human growth hormone production 3. Recombinant protein manufacturing platforms ## Why it matters This patent is a cornerstone of the modern biotechnology industry. It provided the legal and technical framework for producing life-saving human proteins, such as synthetic insulin, which replaced the previous, less-effective method of harvesting insulin from the pancreases of slaughtered cows and pigs. ## Frequently asked questions ### What does How Scientists Taught Bacteria to Make Human Hormones cover? Genentech's 1979 patent on using engineered DNA to force bacteria to produce human proteins like insulin and growth hormones. ### Who owns patent US 4356270? Genentech Inc owns this patent, granted in 1982. ### When does this patent expire? This patent has expired and is now in the public domain — anyone can use the invention freely. ### What is patent US 4356270 cited by? This patent has been cited by 86 later patents that build on its ideas. ### What problem does this patent solve? This patent is a cornerstone of the modern biotechnology industry. It provided the legal and technical framework for producing life-saving human proteins, such as synthetic insulin, which replaced the previous, less-effective method of harvesting insulin from the pancreases of slaughtered cows and pigs. ### What does this patent NOT cover? Does not cover naturally occurring DNA sequences that have not been synthetically modified for microbial expression. **Full plain-English explainer:** https://patentbrief.org/patent/us/4356270/recombinant-dna-cloning-genentech **Original patent:** https://patents.google.com/patent/US4356270 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [How Scientists First Made DNA Replicate in New Cells](https://patentbrief.org/patent/us/4237224/cohen-boyer-recombinant-dna) — This 1980 patent describes a method for cutting and pasting DNA pieces in a lab to create new, self-replicating genetic material that can be inserted into bacteria, a foundational technique for genetic engineering. - [How Scientists Created Bacteria That Eat Oil Spills](https://patentbrief.org/patent/us/4259444/chakrabarty-genetically-modified-bacteria) — A 1981 patent for genetically engineered bacteria capable of breaking down multiple types of oil, which became the first living organism ever patented. - [How to Edit Genes in Human Cells Using an Engineered CRISPR System](https://patentbrief.org/patent/us/8697359/crispr-gene-editing) — This patent describes an engineered CRISPR-Cas9 system for precisely cutting DNA in eukaryotic cells to change how genes work, opening the door for gene editing in complex organisms. - [How to Make Billions of Copies of a DNA Segment](https://patentbrief.org/patent/us/4683195/pcr-polymerase-chain-reaction) — This patent describes the Polymerase Chain Reaction (PCR), a method to rapidly create many copies of a specific piece of DNA or RNA, enabling its detection and analysis. - [How Modified RNA Tricks Cells Into Making Proteins Without Triggering Attacks](https://patentbrief.org/patent/us/8278036/rna-containing-modified-nucleosides-and-methods-of-use-thereof) — A breakthrough method for using modified RNA to deliver instructions to cells without causing the body to reject the treatment as a foreign invader.