Protein "mutant" terms & nomenclature - how we not technically-correctly talk about altered proteins скачать в хорошем качестве

Protein "mutant" terms & nomenclature - how we not technically-correctly talk about altered proteins

How we typically (though not technically-correctly) talk about “mutant” proteins - a hopefully construct-ive chat on the terminology (as I work on doing a bunch of site-directed mutagenesis…) blog form this shortened post is adapted from, which has much more on site-directed mutagenesis techniques (SLIC, Quikchange, etc.): https://bit.ly/mutagenesisconstructs  YouTube:     • Mutation mumbo-jumbo: terminology, types, ...   A protein’s structure comes ultimately from its genetic instructions: the sequence of DNA letters that get copied into RNA letters determines the sequence of proteins letters (amino acids) in a protein. And because those different amino acids have different properties (size, charge, water-likingness), they affect how the protein folds (structure) & how it acts (function). So if you change the gene (introduce a mutation), you can change the protein and potentially its functioning. In the lab, we often do this in precise locations using site-directed mutagenesis to make different versions or “constructs” of the gene & therefore the protein. And in the wild it happens all the time. Speaking of which, we refer to the original, “non-mutated” form as “wild-type” and the changed versions as “mutants.” BUT, technically speaking, the mutation happens at the level of the DNA, not the protein. BUT we biochemists tend to ignore that technicality! BUT it can be an important distinction because not all mutations affect the protein’s sequence (synonymous mutations don’t) - more here: https://bit.ly/mutation_terms ;YouTube:    • Mutation mumbo-jumbo: terminology, types, ...   Mutation types include… substitutions (change some DNA lteters) these can be drastic (such as changing a negatively-charged aspartate to a positively-charged arginine) or “conservative” (such as shifting around the atoms of leucine to get isoleucine which acts pretty darn similarly) insertions (add some DNA lettttters) deletions (remove some DNA ltrs) when we shorten the ends we typically refer to these changes as “truncations.” If you cut off part of the “starting end” of the protein we call it an N-terminal truncation and if you cut off part of the “ending end” we call it a C-terminal truncation Some notations we use to describe what’s happened: For substitutions, we put the original letter first & what it’s changed to afterwards. So, say the 91st amino acid was changed from a glycine (G) to an alanine (A). You could write this as G91A. And if the 215th amino acid was changed from A to G you’d write A215G to indicate taking out stretches of amino acids, we use the delta sign, Δ. So if we (or evolution) removed amino acids 80-100, we would write Δ80-100. I do a lot of cloning. I mean a lot… I keep a spreadsheet with all of the different “constructs” I’ve made (and a few I’ve inherited from former lab members). A “construct” is basically just a plasmid containing some version of a sequence. So I can have a “wild-type” (unmutated) construct of protein X and then a G215A construct of protein X, which I might write as X(G215A). And then I might have X(Δ315-350) (a deletion construct), etc. And then I might have a bunch of constructs of protein Y, and Z, and…. End result - going into my thesis defense my spreadsheet had over 175 constructs… It can get unwieldy to write out things like X(G215A;C298Q;F300G;T474A) over and over again, especially on a tiny test tube! So, to make things easier to keep track of, I give each construct an inventory number like “15786” and “15787” (the actual numbers correspond to their spot in a lab database). These numbers are super helpful until you forget that other people can’t know what you’re talking about without you telling them what construct they correspond to… more on crystallography: http://bit.ly/xraycrystallography2   more on protein structure: https://bit.ly/proteinstructure  more on sickle cell anemia: http://bit.ly/valinevalue &    • Sickle cell anemia and valine biochemistry   more on Huntington’s disease: http://bit.ly/glutaminehd &    • Huntingtons disease biochemistry, genetic ...          more about all sorts of things: #365DaysOfScience All (with topics listed) 👉 http://bit.ly/2OllAB0 or search blog: http://thebumblingbiochemist.com