I am a research scholar working on this protein called pregnancy zone protein (PZP). I was facing problem in getting western blot bands of the same, so I checked the literature and found this paper,
Sun Z, Wang T, Hou X, Bai W, Li J, Li Y, Zhang J, Zheng Y, Wu Z, Wu P, Yan L, Qian H. Mesenchymal stromal cells-derived small extracellular vesicles protect against UV-induced photoaging via regulating pregnancy zone protein. Stem Cells Transl Med. 2024 Nov 12;13(11):1129-1143. doi: 10.1093/stcltm/szae069. PMID: 39425900; PMCID: PMC11555477.
This paper has reported the size of protein in western blot as 126kDa however the literature and antibody catalogue sas that the size is approx 164-180kDa. I do not understand how this is possible. Can anyone help me to understand this. I will be great help.
Reference for PZP molecular weight:
1. https://www.uniprot.org/uniprotkb/P20742/entry#ptm_processing
2. https://www.ptglab.com/products/PZP-Antibody-21742-1-AP.htm?srsltid=AfmBOopC5lkcqATCTiNHov8jy_6LPIQPEPo6dnkK9XzVR1Qj1JbsmojC
Hello Neha,
Pregnancy Zone Protein (PZP) is a large, dimeric protein (360 kDa) composed of 180 kDa subunits. It has a bait region that is crucial for its function. PZP has a variable molecular size primarily due to fragmentation of the bait region by proteinases. PZP is a proteinase-binding molecule, and when proteinases interact with its bait region, they can cleave it, leading to a change in molecular weight. So, the molecular size of PZP is not fixed. It can change because of proteinase interactions and the subsequent cleavage of the bait region.
Antibodies are designed to bind to a specific part of a protein called an epitope. Antibodies for PZP can still recognize the protein on Western Blot even if it is fragmented because they target specific epitopes on the protein, and these epitopes may remain intact even after protein degradation or fragmentation.
The antibody catalogue may specifically list the size of the monomer subunit (approx. 164-180kDa) because they target the individual subunit, not the entire dimeric structure. In some cases, the monomer subunits can be partially cleaved or fragmented, potentially resulting in lower molecular weight (such as the one reported in the paper as 126 kDa; doi: 10.1093/stcltm/szae069).
Best,
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