What method is used to detect the level of protein expression in cells

The protein content determination method is to detect the n element.

content, like melamine.

The problem is that the "protein" content is increased by increasing the amount of n.

The national standard method for detecting protein content is called Kjeldahl method, and the protein in food is decomposed under catalytic heating conditions, resulting in the combination of ammonia and sulfuric acid to produce ammonium sulfate.

Alkali distillation uses sulfur-free, boric acid absorption, titration with sulfuric acid or hydrochloric acid standard titration solution, nitrogen content is calculated according to acid consumption, and then multiplied by the conversion factor, i.e., protein content.

<>, the expression level of a protein in the cell refers to the rate and amount of protein synthesis in the cell. Normally, protein expression levels within cells are affected by gene transcription and translation. Intracellular protein expression levels can be affected by external factors such as drug and viral infections, and may also change due to regulatory mechanisms within the cell.

Studying the expression level of a protein in cells can help people understand the role that the protein plays in cells, thus providing new ideas for diseases.

The easiest way to look at the difference in protein is to look at the molecular weight, unless it is a dimer with a two-fold or four-fold relationship, and the molecular weight of tetramer is generally different.

The easiest way to look at the molecular weight is to run the gel. If you want to compare the differences in the proteins expressed by 7 cells, you can:

1) A large number of 7 types of cells were cultured;

2) Depending on what cell you are, lysate, extract proteins. If it is bacteria, you can use ultrasound or pressure to break them, and if it is a mammalian cell, you can buy a ready-made protein solution and centrifuge it.

3) Prepare the SDS page, you can use denaturing each cell to run one, contrast the glue, if it is different, it is different.

4) If you are concerned about a certain protein, you can label that protein with a tag such as his tag in the early stage, and then isolate it and do mass spectrometry, and you can also see the difference.

Answer] Big grip: Leather head c

Southern blotting is used for DNA detection; RNA blotting is used for RNA detection; Western blotting is used for the detection of proteins, which can analyze the smooth expression of proteins; PCR is often used for the amplification of DNA of purpose in vitro.

Expression is divided into transcription and translation processes.

Transcription is the formation of messenger RNA that does not affect the nucleotide sequence.

Then it should be the addition or deletion of individual base pairs during transcription that causes changes in the amino acid sequence, which ultimately affects the formation of proteins.

1 DNA level: epigenetic regulation such as DNA methylation;

2. Transcription level: specific transcription factor regulation;

3. Post-transcriptional regulation: RNAi affects mRNA level and then protein level;

4. Translation level regulation: specific translation factor, or stabilization factor;

5. Post-translational regulation: phosphorylation, ubiquitination, etc., affecting the stability of proteins.

A. Different kinds of proteins exercise different functions, the more types of proteins in the cell, the more complex the functions of the cell are usually the more complex the cells are, a error b. There are carrier proteins that carry substances on the cell membrane, enzymes that play a catalytic role in the cytoplasm, and there are proteins bound to DNA on the chromosomes in the nucleus, different types of proteins have different functions and are the main bearers of life activities, b correct C, DNA mainly exists in the nucleus, RNA mainly exists in the cytoplasm, C error D, The genetic material in the nucleus and cytoplasm of human cells is DNA, and only a few viruses contain only RNA in the genetic material that is RNA

If you know which protein to detect, just do real time and western.

If you don't know, you just want to see what proteins are on the cell membrane, then it's more troublesome, you have to use gradient centrifugation to separate the proteins on the membrane, and then do mass spectrometry.