Protein biosynthesis (or protein synthesis) is a core biological process, occurring inside cells, balancing the loss of cellular proteins (via degradation or export) through the production of new proteins. Proteins perform a variety of critical functions as enzymes, structural proteins or hormones and therefore, are crucial biological components. Protein synthesis is a very similar process for both prokaryotes and eukaryotes but there are some distinct differences.

Protein synthesis can be divided broadly into two phases - transcription and translation. During transcription, a section of DNA encoding a protein, known as a gene, is converted into a template molecule called messenger RNA. This conversion is carried out by enzymes, known as RNA polymerases, in the nucleus of the cell. In eukaryotes, this messenger RNA (mRNA) is initially produced in a premature form (pre-mRNA) which undergoes post-transcriptional modifications to produce mature mRNA. The mature mRNA is exported from the nucleus via nuclear pores to the cytoplasm of the cell for translation to occur. During translation, the mRNA is read by ribosomes which use the nucleotide sequence of the mRNA to determine the sequence of amino acids. The ribosomes catalyse the formation of covalent peptide bonds between the encoded amino acids to form a polypeptide chain.

Following translation the polypeptide chain must fold to form a functional protein, for example, to function as an enzyme the polypeptide chain must fold correctly to produce a functional active site. In order to adopt a functional three-dimensional (3D) shape, the polypeptide chain must first form a series of smaller underlying structures called secondary structures. The polypeptide chain in these secondary structures then folds to produce the overall 3D tertiary structure. Once correctly folded, the protein can undergo further maturation through different post-translational modifications. Post-translational modifications can alter the protein's ability to function, where it is located within the cell (e.g. cytoplasm or nucleus) and the protein's ability to interact with other proteins.

Protein biosynthesis has a key role in disease as changes and errors in this process, through underlying DNA mutations or protein misfolding are often the underlying causes of a disease. DNA mutations change the subsequent mRNA sequence, which then alters the mRNA encoded amino acid sequence. Mutations can cause the polypeptide chain to be shorter by generating a stop sequence which causes early termination of translation. Alternatively, a mutation in the mRNA sequence changes the specific amino acid encoded at that position in the polypeptide chain. This amino acid change can impact the proteins ability to function or to fold correctly. Misfolded proteins are often implicated in disease as improperly folded proteins have a tendency to stick together to form dense protein clumps. These clumps are linked to a range of diseases, often neurological, including Alzheimer's disease and Parkinson's disease.

Medical Physics and Applied Sciences is a journal published Triannualy in English language. We welcome original research articles, review articles, editorials, case reports, and others from any part of the world. Manuscripts are reviewed by members of the international editorial board and our expert peer reviewers, then either accepted for publication or rejected by the chief editor. Shorter articles are particularly welcome.

Authors are welcome to submit their manuscripts. Submit manuscript at https://www.scholarscentral.org/submission/insights-medical-physics.html (or) as an e-mail attachment to medicalsci@scholarlymed.com or medicalsci@medicinaljournals.com

Media contact

Eliza Miller

Managing Editor

Journal of Medical Physics and Applied Sciences