70 votes
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What is the longest-lasting protein in a human body?

Crystallin proteins are found in the eye lens (where their main job is probably to define the refractive index of the medium); they are commonly considered to be non-regenerated. So, your crystallins ...
Mowgli's user avatar
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22 votes

What is the longest-lasting protein in a human body?

I like Mowgli's answer, because it is a non-obvious example. However I would also point out that there are many, many protein-based structural components in the body that we know do not regenerate due ...
Meep's user avatar
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13 votes
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Viral vector vaccines - why doesn't the viral vector get attacked by the innate immune system?

These Chimpanzee adenoviral vectors do not bypass the innate immune system at all. In fact they are used precisely because of their activation of the innate immune system, which then results in ...
bob1's user avatar
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11 votes

Bacterial cells disappearing from culture with time

That sounds like phage. The pattern of initial growth followed by catastrophic death with some cell debris is classic for induction and lysis. Have you observed anything strange on plates? You could ...
ksdjnf's user avatar
  • 186
10 votes

What is the longest-lasting protein in a human body?

A very interesting example are the cohesin molecules holding sister chromatids together in the oocytes (so only applicable to females, sorry!). Cohesion is established in utero, and these molecules ...
Phlya's user avatar
  • 201
9 votes
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Is alternative splicing possible in the same cell?

In complex eukaryotes like humans, alternative splicing is the rule, rather than the exception. Eukaryotic splicing is managed by a complex regulatory system, including more than 100 different ...
jakebeal's user avatar
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6 votes
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Reason behind using inducible promoter for heterologous expression

Heterologous promoters often express genes that are toxic to the organism when expressed in too high quantities. When the genes are expressed constitutively, the organism will either grow slowly or ...
March Ho's user avatar
  • 9,442
6 votes

Viral vector vaccines - why doesn't the viral vector get attacked by the innate immune system?

The innate immune system has many different components to it. If we consider a natural virus, like the base adenovirus used as a vector used in the Oxford/AstraZeneca vaccine, then we can assume that ...
jakebeal's user avatar
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5 votes
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If bortezomib, a cancer drug, inhibits cell proteasomes, wouldn't resulting protein aggregate in normal cells further increase the risk of cancer?

Proteasome inhibitors do affect normal cells to some extent, but the whole point of using them as cancer treatments is that (some) cancer cells are far more sensitive to proteasome inhibitors than are ...
iayork's user avatar
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5 votes

What's the best way to purify my His tagged protein? Supernatant super viscous after first sonication?

As Chris said in the comments, make sure you have sufficient DNase in your lysis buffer. That combined with good sonication will definitely shear nucleic acids and make your solution less viscous. If ...
MattDMo's user avatar
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4 votes

Are there any examples in nature of two polypeptides joining into a single, continuous, third polypeptide?

I am not aware of anything precisely corresponding to your diagram, but the somewhat related behaviour of inteins may be of interest in this respect. They are defined in Wikipedia as: An intein is ...
David's user avatar
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4 votes
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How can I render a protein non-functional to avoid problem during expression?

Inclusion body (IB) is a technique used to express proteins that are toxic to the host cells. IBs are aggregate of highly similar or the same kind of proteins in the cytoplasm formed as stress ...
Leading Biology's user avatar
4 votes
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Quantifying Gene Expression

What is Protein Expression Level? This was the original title of the post, which I edited myself because I regard the answer as trivial, but the question as more substantial. To deal with the trivial ...
David's user avatar
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4 votes
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How broad are the conclusions that one can make from a heterologous expression experiment?

GSK3 is interesting because as a kinase, it is itself regulated by its phosphorylation status (particularly by Akt in neurons). Therefore, more protein does not necessarily mean more activity. For ...
Jei Diwakar's user avatar
4 votes
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Why are heterologous expression systems such as mammalian cell lines commonly used for studying interactions between neuronal proteins?

One of the advantages you already stated that depending on protein of interest if it's already expressed in CHO cell line, researchers use that. Apart from that, this question is more of a general ...
Science123's user avatar
3 votes
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Can different proteins be produced during translation of a single mRNA in eukaryotes?

There are multiple mechanisms that are known to lead to translation of substantially (or entirely) different proteins from a single mRNA. While these mechanisms are more typically seen in viruses, I'm ...
tyersome's user avatar
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3 votes
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The genetic code and the effect of point mutations on proteins

Nonambiguity refers to the fact that codon X will always code for the same amino acid. Degeneracy refers to the fact that an amino acid can be coded for by many codons. I rephrase the question to ...
S Pr's user avatar
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3 votes

Why is sorbitol used in buffers?

Generally, sorbitol is one of those 'old tricks' in the book which is thrown into cultures or buffers for several reasons. Here are a few that I have heard of: Bacterial cultures (e.g. E.coli BL21) ...
CuriousTree's user avatar
3 votes

What is the longest-lasting protein in a human body?

In terms of the common/abundant proteins, the answer would have to be elastin. The turnover is extremely slow, with a half-life of 74 years (https://www.elastagen.com/media/The_Science_of_Elastin....
Alex I's user avatar
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3 votes
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Why does it matter to predict protein structure?

How do you want to predict function and binding partners without knowing how your protein looks like? The sequence itself contains only limited information. Similar sequences might fold into similar ...
Frieke's user avatar
  • 1,127
3 votes

Protein bands not visible after sds page coomassie dye stain

The problem here is concentration. Coomassie Blue stain can only detect protein band greater than or near to 50ng, in this case, the concentration of your protein is too low for detection. If you want ...
Leading Biology's user avatar
3 votes

Are there any examples in nature of two polypeptides joining into a single, continuous, third polypeptide?

Does splicing of peptides in the proteasome count? Proteasomes normally degrade proteins into small peptides, but the process is conceptually reversible -- peptide bonds can be generated as well as ...
iayork's user avatar
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3 votes
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Is protein production doubled if you have homozygous dominant genes as opposed to heterozygous genes?

Dominance is defined based on the phenotype Dominance is defined based on a phenotype of interest. Pick a phenotype, say coat color for example. If genotypes AA ...
Remi.b's user avatar
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3 votes

Gene vs. Protein Expression Assays

Gene expression is the production of a functional gene product from a gene. So protein expression is a functional read-out of gene expression for gene loci that encode proteins. However, gene ...
Michael_A's user avatar
  • 1,305
3 votes

How to put a gene under the control of a regulable promoter?

If you're expressing the gene in E. coli, then you're almost certain to be using a plasmid or other ectopic gene vector. There are a wide variety of plasmids available, with many different promoters. ...
Forest's user avatar
  • 1,879
2 votes

T7 vs pBAD promoter strength

The exact numbers depend on the protein. In my hands, I would say between the pAraBAD and a pLac-T5 you can expect some fold improvement and pAraBAD and a pT7 promoters you can expect about an order ...
Matteo Ferla's user avatar
2 votes

Methods for varying insert size in E. coli clones

Yes. In principle you will have a vastly increased ability to customize the boundaries of each protein domain with a primer and PCR based approach. It is not obvious to me that the Gateway Cloning ...
mdperry's user avatar
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