The introduction of antibodies that specific to internal control protein (III)

As we all know, internal control proteins are expressed by house keeping genes. These proteins show relatively constant quantity in different tissues and cells. When we arranged an experiment to test the expression of target proteins, they could be considered as a reference in the experiment.

The internal control proteins often are used in the Western Blot. Western Blot can not only be used to prove whether the samples contain the target protein, it also can be used for discriminating the difference of protein quantity among different samples and different conditions. So Western Blot is usually designed for protein expression level test. Internal control proteins as a reference, are used to determine the consistence of samples, for instance, quantity of tissue, cell, loading sample, etc, and correct the operate error in the experiment, to further ensure the accuracy of the result. For different target proteins, how to choose the internal control proteins?

We have introduced the selection and application of several common internal control proteins before. This time we will give a systematic introduction to the selection of different internal control proteins and antibodies which are produced by Cloud-Clone Corp..

For the choice of internal control proteins, molecular weight is the first factor to consider. In generally, it is recommended that the difference between the MW of the internal control protein and target protein should be larger than 5kDa. For example, if the MW of target protein is 45kDa, we will choose Tubulin Beta (54kDa), Lamin B1 (66kDa) as the internal control protein, but not ACTa2 (42kDa) or beta-actin (45kDa).

Next, for different tissues, the different internal control proteins should be chosen. For instance, actin is a cytoskeletal protein, it includes 6 subtypes, including alpha-skeletal muscle actin, alpha-cardiac muscle actin, alpha-smooth muscle actin, gamma-smooth muscle actin, beta-actin (β-non-muscle) and gamma-non-muscle actin. The common used beta-actin shows a very low abundance in muscle and adipose tissue, so if we want to test the protein which is expressed specifically in heart or adipose tissue, other internal control proteins should be used, such as alpha-cardiac muscle actin (ACTC1) or GAPDH.

Lastly, the choice of internal control protein is also related to the target protein’s subcellular localization. Sometimes, cytoplasm protein or nucleus protein are extracted, but not total protein, so the internal control protein should be chosen by its subcellular localization. Such as PCNA is expressed stably in nucleus, but not expressed in cytoplasm in theory. So, if we extract the cytoplasm protein, beta actin and Tublin Beta could be used for internal control protein, but not PCNA.

Cloud-Clone Corp. has launched a series of control antibodies to meet the customers’ demand. Different antibodies can be chosen to target proteins which are expressed in different tissues, have different subcellular localization or molecular weight. Shown in table 1.

Table 1: control antibodies

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