The protein band in the western blot is different from the predicted molecular weight of the protein. What might be the possible reason?
- Post-tanslational modification, such as phosphorylation, glycosylation, etc. All of these may increase the protein molecular weight.
- Post-translational cleavage: for protein processing, i.e. cleavage from a precursor to a mature active form, such as occurs with a caspase precursor.
- Splice variant: isoforms from alternative splicing.
- Relative charged-amino acid composition (the ratio of both charged and uncharged amino acids).