Cells’ ability to replace proteins lost to degradation or export is maintained through a process known as protein biosynthesis, which occurs inside cells. Enzymes, structural proteins, and hormones are all examples of proteins that play vital roles in the body. Prokaryotes and eukaryotes have a lot in common when it comes to protein production, but there are some notable variances.
Transcription and translation are the two main stages of protein synthesis. It is during this process of transcription that a gene, which encodes a protein, is transformed into messenger RNA (mRNA). Enzymes in the cell nucleus called RNA polymerases perform this process. Premature mRNA (pre-mRNA) is synthesized in eukaryotes and then modified post-transcriptionally to generate mature mRNA. Translation may begin only once the mature mRNA has been exported from the nucleus to the cytoplasm of the cell through nuclear pores. The nucleotide sequence of the mRNA is used by ribosomes to determine the amino acid sequence during translation. The polypeptide chain is formed by the covalent peptide bonds formed by the ribosomes between the encoded amino acids.
It is necessary to fold the polypeptide chain appropriately to generate an active site in an enzyme after translation in order for the chain to operate as a functioning protein. The polypeptide chain must first create a succession of smaller underlying structures known as secondary structures before it can assume a functional three-dimensional (3D) shape. To create the overall 3D tertiary structure, these secondary structures fold the polypeptide chain. Different post-translational modifications may be applied to the protein after it has been successfully folded. The protein’s capacity to function, where it is situated within the cell (e.g. cytoplasm or nucleus), and the protein’s ability to interact with other proteins may all be affected by post-translational changes.
If the DNA mutations or protein misfolding that cause an illness are shown to be related to alterations in protein production, then this process plays an important part in the disease. DNA mutations modify the mRNA sequence, which in turn modifies the amino acid sequence encoded by the mRNA. An early end of translation is caused by the generation of an early stop sequence in the polypeptide chain, which may be shortened by mutations. Alternately, the exact amino acid expressed at that location in the polypeptide chain may be changed by a mutation in the mRNA sequence. The protein’s ability to function or fold appropriately may be harmed by this amino acid substitution. Misfolded proteins are often linked to illness because they tend to form dense protein clumps when they are misfolded. Alzheimer’s and Parkinson’s illnesses, among others, have been related to the presence of these aggregates.
