If no signal is detected in a total cell extract, it is worth fractionating, to obtain specific chloroplast, mitochondria or nuclei enriched fractions. This procedure will concentrate a target protein and lead to the detection of a desired band (for non-cytoplasmic proteins). This is shown in the example above - from no band in a total cell extract, to a specific band in photosystem I fraction.
This approach is especially important when working with proteins of low expression. Fractionation combined with using a specific organ, e.g. the root tip, or a leaf at a certain developmental stage, will greatly contribute to the successful identification of your protein of interest.
Examples of protocols to fractionate can be found here.
For Agrisera Western Blot Guide and video tutorials, check here.
In case of any questions, you are always welcome to contact Agrisera Technical Support.